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OCR 21st Century Science: P1 The Earth in the Universe

COLLINS NEW GCSE SCIENCE © HarperCollinsPublishers Ltd 2011

P1 Module Introduction

Pages 202−203 in the Student Book provide an introduction to this module.

When and how to use these pages

These pages summarise what students should already know from KS3 or previous GCSE units and provide an

overview of the content that they will learn in this module.

o Use these pages as a revision lesson before you start the first new topic. o Brainstorm everything that students remember about the different topics using the headings as a starting point. Compare your list with the points on page 202. o Use the questions on page 202 as a starting point for class discussions. o Ask students if they can tell you anything about the topics on the right-hand page. o Make a note of any unfamiliar / difficult terms and return to these in the relevant lessons.

Suitable answers to the questions on page 202 are:

o The Moon. o Images of different objects from the all parts of the Universe using light and other electromagnetic waves. o Formed deep inside the Earth from sedimentary and igneous rocks, when very high temperatures and

pressures are applied.

You could revisit these pages at the following points:

o before lesson p1_07 on rocks, Student Book pages 218−219 o before lesson p1_10 or p1_11 on waves, Student Book pages 224−225 / 226−227

Overview of module

In this module students will learn about the solar system and the different objects it contains, how scientists use

telescopes and radiation to study the solar system and the wider Universe, and the difficulties in measuring vast

distances accurately. Students will also learn how fusion in stars accounts for all the elements found in the

Universe, that redshift provides evidence for the expanding Universe, why scientists believe the Universe began as

a Big Bang and what they think its possible fates could be.

Students will learn how rocks on Earth are constantly changing, what causes these changes and their effects. They

will learn about continental drift and the evidence for these ideas, and about the theory of tectonic plates and how

the movement of these plates accounts for phenomena such as earthquakes, new mountains and volcanoes.

Students will also learn about seismic waves, how scientists use these to study the internal structure of the Earth,

and the differences between longitudinal and transverse waves. They will learn what a wave is, how to calculate its

speed and other wave properties and features.

Obstacles to learning

Students may need extra guidance with the following terms and concepts:

The solar system and the Universe

The large number of new terms may cause confusion. Use different ways to introduce, reinforce and link

terminology. It is hard for students to comprehend the scale of distances and sizes in the Universe, and the

numbers involved are very large. Although parallax is an everyday phenomenon, students may struggle to apply it

to distant stars. Try to include as many practical examples and use the internet as there are many suitable

animations.

Nuclear fusion

This topic is very conceptual because it involves reactions that cannot be shown in a lab − nuclear reactions, rather

than chemical reactions. Students may be unfamiliar with the concept of the nucleus as part of the structure of

atoms. Try to include as many practical examples, images and animations as possible.

The Big Bang

There is no direct evidence for the Big Bang that students can identify with. The timescale ranges from billions of

years ago that the events took place, to major changes taking place in fractions of a second. The actual events that

occurred are beyond any ideas that students will have come across before. Try to include as many images as

possible to give students a model that they can relate to. The expansion of the Universe is hard for students to

grasp because they must consider wave behaviour (stretching wavelengths), a moving source of light, conclusions

P1 Module Introduction continued


from an analysis of the light (line spectra) and the significance of line spectra (the unique fingerprint of different

elements).

Rocks on Earth

Students may think the landscape does not change. Particularly in the UK, changes to the landscape take place

over a very long time, so it can be hard for students to conceive that the structure of the landscape really is

changing slowly over a very long timescale. They can’t make direct observations or measurements so must rely on

indirect evidence. Students may confuse tectonic plates with land masses. Show them a map with the position of

tectonic plate boundaries and the continents clearly marked.

Waves

It can be hard for students to visualise waves transferring energy without transferring matter. Seismic waves are

beyond the experience of most students, and some may be distracted by the destructive effects of a powerful

earthquake, rather than focusing on seismic waves and their properties. Students can find it hard to apply the

terminology of waves to the diagrams, and relate this to what is actually happening. Although water waves and

waves on a slinky spring and a rope are easy to visualise, it is harder to visualise electromagnetic waves, seismic

waves or sound waves. Some students struggle with the ‘inverse proportion’ ideas (frequency and wavelength;

frequency and time per wave cycle).

Practicals in this module

In this module students will do the following practical work:

o Comparing relative brightness of bulbs of different intensity at different distances. o Using a ripple tank the help understanding of the wave equation.

Key vocabulary covered in this module

solar system planet dwarf planet asteroid comet moon light-year

Universe galaxy Milky Way light-year radiation data hypothesis theory

real brightness relative brightness light pollution parallax

nuclear fusion supernova

redshift

Big Bang

erosion sediments fossils volcano crater geologist sedimentation crust

continental drift convection seafloor spreading oceanic ridge

tectonic plate plate boundary magma fold mountain rock cycle plate tectonics

crust mantle seismic waves P-waves S-waves shadow zone longitudinal transverse

wave amplitude wavelength oscilloscope

frequency hertz wave equation inversely proportional



P1 Module Checklist

Pages 230−231 in the Student Book provide a student-friendly checklist for revision.


This checklist is presented in three columns showing progression, based on the grading criteria. Bold italic means

Higher tier only.

Remind students that they need to be able to use these ideas in various ways, such as:

o interpreting pictures, diagrams and graphs

o applying ideas to new situations

o explaining ethical implications

o suggesting some benefits and risks to society

o drawing conclusions from evidence they have been given.

These pages can be used for individual or class revision using any combination of the suggestions below.

o Ask students to construct a mind map linking the points on this checklist.

o Work through the checklist as a class and note the points that need further class discussion.

o Ask students to tick the boxes on the checklist worksheet (on the Teacher Pack CD) if they feel confident that they are well prepared for the topics. Students should refer back to the relevant Student Book pages to revise the points that they feel less confident about.

o Ask students to use the search terms at the foot of the relevant Student Book pages to do further research on the different points in the checklist.

o Students could work in pairs, and ask each other what points they think they can do, and why they think that they can do those, and not others.

P1 Module Checklist continued


Module summary

In the introduction to this module, students were presented with a number of new ideas. Work through the list

below as part of their revision. Ask students to write their own summaries and mind maps, using this list as a

starting point.

The solar system and the Universe

o there are different types of objects in our solar system

o stars are grouped in vast galaxies

o we can observe stars, analyse their light and determine their distance from us

o nuclear fusion in stars generates heat, light and new elements

o the Universe is believed to have been created in a Big Bang and it is still changing

Rocks on Earth

o rocks on Earth are undergoing continuous change

o there is evidence that the continents have moved over a long timescale

o tectonic plate movements cause earthquakes, volcanoes and mountain formation

o earthquakes are detected by the waves they produce in the Earth

o these waves can tell us about the structure of the Earth and its crust

Waves

o energy can be transferred by waves

o the behaviour of waves depends on whether the waves are transverse or longitudinal, and on their wave speed, wave frequency and amplitude



Checklist P1 Aiming for A

Use these checklists to see what you can do now. Refer back to the relevant topic in your Student Book if you are not sure. Look across the rows to see how you could progress – bold italic means Higher Tier only.

Remember that you will need to be able to use these ideas in various ways, such as:

interpreting pictures, diagrams and graphs

applying ideas to new situations

explaining ethical implications

suggesting some benefits and risks to society

drawing conclusions from evidence that you are given.

Working towards an A grade

Aiming for Grade C Aiming for Grade A

recall the names, relative sizes and motion of different bodies in the solar system and the wider Universe;

recall that the Sun is just one of the thousands of millions of stars in the Milky Way galaxy;

recall that the Universe contains thousands of millions of galaxies which each contain thousands of millions of stars

use appropriate units, including the light-year, for describing distances in the Universe

understand how we can learn about distant stars and galaxies using their radiation, although light pollution and atmospheric conditions interfere with these observations

understand why the finite speed of light means we see distant objects in the Universe as they were in the past;

understand why our observations of distant objects may be unreliable

understand how nuclear fusion forms all the different elements in stars and provides the stars’ energy

describe how the relative brightness of stars and stellar parallax help us to measure the distances to stars

understand methods of measuring distances to stars, and explain some problems with making and interpreting these measurements

understand that the observed movement of distant galaxies away from us gives an approximate age of the Universe

understand that redshift tells us that more distant galaxies move away faster, so space itself may be expanding

OCR 21st Century Science: P1 Checklist


Aiming for Grade C Aiming for Grade A

understand that problems in measuring distances to and motion of distant objects mean that the future of the Universe cannot be accurately predicted

understand why problems measuring the distances to and motion of distant objects and the mass of the Universe cause uncertainty in predicting its ultimate fate

understand that the Earth is older than its oldest rocks

explain the implications of the Earth being older than its oldest rocks

explain how rocks and rock processes seen today provide evidence for past changes

understand and compare how rocks and rock processes seen today provide evidence for past changes

explain how Wegener’s theory of continental drift was developed and modified

understand implications of Wegener’s theory of continental drift and why geologists at first rejected it

understand that heating of the core causes convection in the mantle, and seafloor spreading

understand the causes of seafloor spreading, and what the magnetisation of seafloor rocks can tell us

understand that earthquakes, volcanoes and mountain building generally occur at the edges of tectonic plates

understand how moving tectonic plates cause earthquakes, volcanoes and mountain building

describe the features of P-waves and S-waves, and how they give evidence for the Earth’s structure

understand how differences in P-waves (longitudinal waves) and S-waves (transverse waves) give evidence about Earth’s structure

recall that waves are disturbances that transfer energy

explain how waves transfer energy

use the terms wavelength, frequency and amplitude;

draw and interpret diagrams showing amplitude and wavelength

understand the difference between a transverse and longitudinal wave

use equations involving wave speed

use and rearrange the wave equation



Checklist P1 Aiming for C

o achieve your forecast grade in the exam you will need Use these checklists to see what you can do. Refer back to the relevant topic in your Student Book if you are not sure.

Remember that you will need to be able to use these ideas in various ways, such as:

interpreting pictures, diagrams and graphs

applying ideas to new situations

explaining ethical implications

suggesting some benefits and risks to society

drawing conclusions from evidence that you are given.

Working towards a C grade

Aiming for Grade E Aiming for Grade C

recall the names, relative sizes and motion of different bodies in the solar system and the wider Universe;

recall that the Sun is just one of the thousands of millions of stars in the Milky Way galaxy;

recall that the Universe contains thousands of millions of galaxies which each contain thousands of millions of stars

recall that light travels through space at 300 000 km/s;

recall that a light-year is the distance travelled by light in a year

use appropriate units, including the light-year, for describing distances in the Universe

describe how we use the radiation from distant stars and galaxies to detect them

understand how we can learn about distant stars and galaxies using their radiation, although light pollution and atmospheric conditions interfere with these observations

recall that nuclear fusion is when two nuclei join together, forming a new element; and understand that nuclear fusion of hydrogen is the source of the Sun’s energy

understand how nuclear fusion forms all the different elements in stars and provides the stars’ energy

describe how we can measure distances to stars by comparing their brightness

describe how the relative brightness of stars and stellar parallax help us to measure the distances to stars

understand that the Universe began about 14 thousand million years ago, and that distant galaxies are moving away from us

understand that the observed movement of distant galaxies away from us gives an approximate age of the Universe

OCR 21st Century Science: P1 Checklist


Aiming for Grade E Aiming for Grade C

understand that the Universe may be different in the future; and understand there are some difficulties in predicting the future of the Universe

understand that problems in measuring distances to and motion of distant objects mean that the future of the Universe cannot be accurately predicted

recall that the oldest rocks on Earth are about 4 thousand million years old

understand that the Earth is older than its oldest rocks

describe some rock processes taking place today and what they suggest about the past

explain how rocks and rock processes seen today provide evidence for past changes

recall that continental land masses are moving very slowly and that this was described by Wegener in his theory of continental drift

explain how Wegener’s theory of continental drift was developed and modified;

understand that heating of the core causes convection in the mantle, and seafloor spreading

understand that earthquakes, volcanoes and mountain building generally occur at the edges of tectonic plates

understand that earthquakes produce P-waves and S-waves which can be detected; draw and label a diagram of the Earth’s interior

describe the features of P-waves and S-waves, and how they give evidence for the Earth’s structure

recall that waves are disturbances that transfer energy;

use the terms wavelength, frequency and amplitude;

draw and interpret diagrams showing amplitude and wavelength;

use equations involving wave speed



P1 Evaluating and analysing evidence

Pages 208−209 in the Student Book prepare students for assessment.


This activity provides an opportunity to build and assess the skills that students will use when analysing and

evaluating data.

Ask students to:

o read through the context and tasks, listing any terms that they do not understand o as a whole class or in small groups, discuss the tasks to ensure that all students understand the terminology

used and to clarify what is required o work individually to answer the questions for each task.

If time allows, ask the students to mark one another’s work using the mark scheme provided.

Notes

This activity allows students to analyse evidence and apply their general understanding of the movement of and

conditions on planets in the solar system. The tasks encourage students to think about trends in data and also

about how evidence can be interpreted to form an explanation. The final task sets the work in the context of how

discoveries are made and what the relationship is between developing ideas and the use of evidence.

Answers Task 1

Planets such as Jupiter are bright enough to be seen with the naked eye, whereas Neptune is smaller and

more distant and can only be seen with the aid of a powerful telescope. This is a good example of the way in

which technological advances have aided scientific discoveries.

Neptune is further away from the Sun than Jupiter so we would expect its year length to be much longer and its

temperature to be much lower.

Task 2

The key features of the suggested orbit of the new planet should be:

It is in a position to accelerate Uranus (by gravitational

attraction in its direction of motion) from 1800 to 1822.

It is in a position to decelerate Uranus (by gravitational

attraction in opposition to its direction of motion) after 1822.

It is in a circular or elliptical orbit.

It shouldn’t be violently accelerating or decelerating from one position to another. (Kepler’s second law states that a line joining a planet to the Sun sweeps out equal areas in

equal amounts of time; knowledge of this is certainly not

required but the positions shown should be broadly in

agreement with steady orbital motion).

The predicted orbit should be explained with reference to the changing motion of Uranus.

Task 3

Searching the night sky for ‘new’ objects would be so time-consuming as to be impractical. Calculations can

narrow down the area being observed, and so make observation much more likely to be fruitful.

It is true that the discovery was made on the basis of Le Verrier’s predictions, but it was made at a German

observatory. Like much good science, it was a victory for effective collaboration.

P1 Evaluating and analysing evidence continued


Task 4

Jupiter is much further away from Neptune and so would be affected less. It’s also more massive than Uranus, which would reduce the effect on its orbital motion.

Planets, unlike stars, only reflect light so those in other solar systems are extremely faint. This means that

telescopes need to be powerful and also need to be beyond the Earth’s atmosphere in order to form clear

images. It is only very recently that such technology has been available.

Mark scheme

For grade E, students should show that they can:

o describe the main differences between different bodies in the solar system o understand that light pollution and atmospheric conditions interfere with observations o identify patterns in data.

For grades D, C, in addition show that they can:

o explain the significance of the differences between bodies in the solar system o explain why light pollution is a problem when observing the night sky o explain how predictions can be made from patterns in data.

For grades B, A, in addition show that they can:

o combine ideas about the scale of the solar system and the sizes of various bodies in it to construct explanations

o explain how the availability of evidence may be limited by technological considerations o understand the limitations of predictions that can be made from patterns in data.



p1_01 Our solar system

1 Objects in the solar system

Use your Student Book (page 204) to help you. Write down two differences between each of these pairs of objects in the solar system.

The Moon and a planet

Difference 1…………………………………………………………………………………………..

Difference 2………………………………………………………………………………………….. The Sun and a planet

Difference 1…………………………………………………………………………………………..

Difference 2………………………………………………………………………………………….. An asteroid and a planet

Difference 1…………………………………………………………………………………………..

Difference 2………………………………………………………………………………………….. A comet and a planet

Difference 1…………………………………………………………………………………………..

Difference 2…………………………………………………………………………………………..

2 Comparing the planets

Draw a 30 cm line across the middle of a sheet of A3 paper. Label one end of the line as ‘the Sun’. Mark the position of each planet along the line, using the data from the table on page 205 of the Student Book (so the Earth, for example, is 1 cm from the Sun).

Use the information below to draw each planet to scale. Draw the planets on your piece of paper (or cut the larger planets from coloured paper and attach them) in the marked positions. Some are so close together that they will need to go above or below the line.

A scale of 1 mm = 2000 km diameter gives suitably sized planets.

For example, the Earth will be 12 800 2000 = 6.4 or about 6 mm across on your drawing.

Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

Diameter in km

4800 13 000 12 800 6800 143 000 120 600 51 200 49 600

Diameter on your drawing

6 mm

p1_01 Our solar system continued


3 Exploring the solar system

Find out how fast these travel in space:

light

an unmanned space probe

the Space Shuttle

a manned rocket.

Find out average distances from the Earth to other parts of the solar system – such as the Sun, the Moon, and different planets. Calculate how long it would take for signals or spacecraft to reach these from Earth.

distancetime of flight

time

Use your results to explain which parts of the solar system it is feasible for humans to visit. As well as the time of flight, consider factors such as the suitability of the environment, maintenance of supplies, and so on.



p1_02 Observing stars

1 Galaxies

1 Choose from these words to complete the sentences:

Universe galaxy solar system Sun Milky Way

The …………………………. contains everything that exists. A group of millions of stars is

called a ………………………….. . Our galaxy is called the ………………………….. . The

star at the centre of our solar system is called the ………………………….. .

2 Here is some information about galaxies.

There are thousands of millions of galaxies in the Universe. Each galaxy contains thousands of millions of stars.

Our galaxy, the Milky Way, is spiral shaped. It has spiral arms and a bright centre. Older stars are at the centre, and younger stars are in the arms of the galaxy. We are about halfway along one arm. The galaxy is rotating に it takes about 200 million years to rotate once. Our galaxy is so big that light takes 100 000 years to cross it.

Other galaxies are ellipses Ъ like a fat cigar. Some galaxies have no clear shape.

Use this information, page 206 in the Student Book and information from other sources to make a poster about galaxies suitable for a Year 7 student. Call it ‘The Milky Way’ or ‘Different types of galaxies’. Your poster needs at least one labelled diagram or photo, and must say what a galaxy contains and where galaxies are found. A ‘Milky Way’ poster should include a labelled diagram showing where our solar system is, as well as some facts about the Milky Way. A ‘Different types of galaxies’ poster should list some things that all galaxies have in common, as well as showing some differences.

2 Data, hypotheses and theories

1 Decide if each of these statements consists of data, a hypothesis or a theory.

Statement Data, hypothesis, theory?

A Ptolemy suggested the Sun orbited round the Earth

B Scientists are certain that planets orbit round the Sun, and can predict their positions. Their positions have been measured over several centuries

C Galileo suggested that moons orbit round Jupiter

D Astronomers record the position of planets at different times

E Galileo used a telescope to watch and record small objects moving round the planet Jupiter

p1_02 Observing stars continued


2 Centuries ago, astronomers and mariners studied stars in the night sky, producing star charts. In the Northern hemisphere, there was one bright star that did not change position during the night but always appeared due north. This was called the North Star. Some astronomers believed the North Star has a fixed position in the sky, and that the other stars move around it. Over many years, this idea changed as we learned that the Earth rotated on its axis. The Earth’s rotation explained why the stars seemed to move about a fixed point. The axis of the Earth’s rotation pointed straight at the North Star.

Using the text above, write down an example of

data

a hypothesis

a theory.

3 Hubble Deep Field

The ‘Hubble Deep Field’ image was created when the Hubble space telescope collected light from the same tiny part of the night sky for 10 days. The image contained light from galaxies so distant that we can’t normally see them. Over the 10 days, more and more light was collected until there was enough to analyse. The image contained pictures of galaxies at all distances from us, up to 10 billion light-years away.

(NASA)

1 When did light leave stars that are 10 billion light years away?

2 Why is the Hubble Deep Field image important for people studying the history of the Universe?

3 Astronomers had to count and classify the many objects they could see in the image. Suggest one way to estimate the number of objects in such an image. Use your method to estimate how many galaxies can be seen in the picture.

4 Suggest one way in which astronomers could classify objects in the image as ‘nearby’ or ‘far away’.

5 Use the internet to research more about the Hubble Deep Field image.



p1_03 Comparing relative brightness

P Measuring the brightness of a bulb

Objectives

In this activity you will see how the relative brightness of a bulb depends on its real brightness and on its distance away. Astronomers use this idea when estimating the distance of stars away from Earth.

Equipment and materials

light meter • metre rule • power pack (0−6 V) • connecting leads • 6 V bulb

Method

1 Set up a circuit using a power pack, connecting leads and bulb.

2 Set the supply voltage on the power pack to 5 V. Make sure that light from other groups will not affect your readings. You may need to shield your bulb and light meter from other light sources.

3 Measure the intensity of the light 10 cm from the bulb.

4 Take readings at two other distances from the bulb. Depending on your equipment, distances between 5 and 20 cm from the bulb should be suitable.

5 Now adjust the brightness of the bulb by reducing the supply voltage on the power pack. Take the readings again at the same distances.

Results

Real brightness of bulb

Intensity 10 cm from bulb

Intensity ……… cm from bulb

Intensity ……… cm from bulb

very bright

bright

dim

very dim

Questions

1 What is the difference between ‘real brightness’ and ‘relative brightness’?

2 How did the real brightness of the bulb vary as you changed the supply voltage?

3 How did the relative brightness vary with the distance from the bulb?

4 Write down two pairs of readings for which the bulb has the same relative brightness. This is when the light meter reading for the bulb at one brightness and distance matches, or is similar to, the light meter reading of the bulb at a different brightness and distance.



p1_03 Distances to stars

1 Sizes in the Universe

Cut out the shaded boxes below and stick each one by the measurement in the table that most closely matches its size/distance. Use your Student Book page 210 to help you.

1 mm

1 m

1 km

1000 km

10 000 km

10 million km

100 million km

10 million million km

1 light-year

100 thousand light-years

1 million light-years

distance from London to Inverness (north Scotland)

about 10−15 minutes’ walking distance

distance light travels in a year distance across the Milky Way

thickness of 5 sheets of paper diameter of the Sun

diameter of solar system diameter of the Earth

distance to next galaxy distance from the Earth to the Sun

height of a young child

p1_03 Distances to stars continued


2 Comparing real brightness

Your teacher will use a light meter to measure the light intensity from different light sources. Watch carefully how the light intensity measurement is taken.

Write down the results.

Object Brightness (light intensity)

1 Why was the teacher careful to measure the intensity of each light source at the same

distance?

2 What effect would there be on the readings if the light meter was placed further away?

3 Use the practical sheet ‘Comparing relative brightness’ to do your own experiment to find out how distance from a light source affects its apparent or ‘relative’ brightness.

3 What is parallax?

You will now investigate an effect called parallax. Astronomers use this to make measurements of distances to stars.

Hold up one finger at arm’s length. Move your head to one side so you are looking at your finger from a different angle. The background appears to move behind your finger.

1 Do objects in the closer background appear to move more or less, compared with more distant background objects?

Astronomers make measurements of stars at 6-month intervals, when the Earth is at opposite points of its orbit round the Sun.

Use Student Book page 211 to help you to complete the diagrams on the next sheet.

On Figure 1, draw a line linking the Earth in July with the ‘nearby star’ and the ‘apparent position in July’ of the star being studied.

Repeat this for the Earth and the star in January. Label the parallax angle.

Complete Figure 2 in the same way to show how the parallax angle changes if the star being studied is further away from the Earth.

Draw a line linking the Earth in January with the nearby star. Carry this line on into the distant stars and make a dot. Label this ‘January’.

Repeat this to show the apparent position of the star in July. Mark in the parallax angle for the star.

2 What do you notice about the parallax angle if the star being studied is further from the Earth?

3 Explain why it is easier to investigate stars close to the Sun using parallax than those at a great distance.

p1_03 Distances to stars continued


Figure 1

Figure 2

OCR 21st Century Science: The Earth in the Universe


p1_04 Fusion in stars

1 Making new elements in stars

Are these statements true or false? For any that you think are false, write down the correct statement. Page 212 of your Student Book has more information.

a) Nuclear fusion reactions take place on planets. T F

b) Nuclear fusion reactions form new elements. T F

c) Nuclear fusion between two helium nuclei forms a hydrogen nucleus. T F

d) Nuclear fusion reactions release large amounts of energy. T F

e) Nuclear fusion during a star’s lifetime is the only way new elements form. T F

Part …… Correct statement ………………………………………………………………………..

…………………………………………………………………………………………………………

Part …… Correct statement ……………………………………………………………………...

…………………………………………………………………………………………………………

Part …… Correct statement ……………………………………………………………………...

…………………………………………………………………………………………………………

2 Fusion reactions

1 A star contains just hydrogen nuclei when it first forms. A sequence of fusion reactions takes place inside the star to eventually form heavier elements. Number these word equations to show the order of steps in the sequence of reactions.

2 The question above shows one sequence of fusion reactions that takes place in a star. Several different fusion sequences can form the same elements in a star. Use the periodic table on page 213 of the Student Book to suggest another fusion reaction that could produce: a) oxygen; b) carbon.

hydrogen + hydrogen helium + energy

Step oxygen + helium neon + energy

carbon + helium oxygen + energy

helium + beryllium carbon + energy

helium + helium beryllium + energy

Step

Step

Step

Step

p1_04 Fusion in stars continued


3 Elements in the Sun

Read this article and answer the questions below.

Over 100 years ago, scientists did not know how energy was generated in the Sun. Their calculations used facts they knew at the time. These suggested the Sun was several million years old. Geological and fossil evidence on Earth suggested it was much older.

In 1905, Einstein developed a completely new way of thinking of physics, his theory of relativity. This theory included an equation linking changes in mass to energy.

In 1920, Aston measured the masses of different nuclei. Helium nuclei contain 4 nucleons, and a hydrogen atom contains 1 nucleon. He found the mass of 4 hydrogen nuclei was more than the mass of one helium nucleus, which was unexpected. It seemed some mass was lost when helium formed from hydrogen fusion. Eddington linked this with Einstein╆s equation to suggest the Sun could generate energy from fusion for 100 billion years.

In 1938, Bethe published a paper called ╅Energy production in stars╆. He described a process in which hydrogen fusion in stars formed helium and released energy. He had no evidence, but his calculations of the Sun╆s core temperature were close to measured values, and other calculations matched with observed data.

In the next 40 years┸ other scientists developed Bethe╆s ideas┻ To prove him right┸ they had to decide what evidence to look for, and how to obtain it. In 1932 Pauli suggested that a particle called the neutrino would be emitted during some nuclear reactions, and these were detected in 1959 by Cowan and Reines.

In 1968, Davis designed and carried out an experiment to try to detect neutrinos coming from the Sun, which had been suggested in theory but never actually found before. He found neutrinos, but fewer than expected. Neutrinos were not detected again until 1986, and again fewer than expected.

This suggests that although the theory of what is happening in the Sun is largely correct, there are still details that need to be sorted.

1 Make a list of scientists who carried out practical experiments, and another list of scientists who thought up creative explanations or ideas.

2 Give one reason why creative new ideas are important for scientific discovery.

3 Explain why practical experiments are an important part of developing new theories.

4 Explain why scientists had to develop a new theory of how the Sun generated its energy.

5 How likely do you think it is that this theory of how energy is produced in the Sun is correct?



p1_05 The expanding Universe: Technician sheet


Demonstration of wavelength and pitch

signal generator, connecting leads, loudspeaker, oscilloscope

Observing line spectra

diffraction gratings or hand-held diffraction spectroscopes

Bunsen burner and heatproof mat

selection of salts, e.g. barium chloride, calcium chloride, copper sulfate, sodium chloride

flame test wires

distilled water

Model of expanding Universe

balloons, balloon pumps, marker pens

Method

Demonstration of wavelength and pitch

The details depend on the exact equipment you have. Check the setup before the demonstration and note the settings that give a successful image on the screen.

Turn the oscilloscope on and adjust it to give a horizontal trace across the centre.

Connect the output of the signal generator to the loudspeaker and to the Y input of the oscilloscope. Refer to the instructions for the model of signal generator that you have.

When the signal generator is switched on and set to about 500 Hz, you will hear a sound from the loudspeaker. Adjust the time-base setting (horizontal scale) and the Y–gain (vertical scale) of the oscilloscope so that a wave can be seen on the screen.

Change the setting on the signal generator to adjust the frequency of the signal across a fairly small range – so you can show the wavelength changing without needing to alter the oscilloscope settings.

Observing line spectra

Darken the room.

Dampen a flame test wire in distilled water and dip it into one of the salts.

Wearing eye protection, hold the flame test wire in a Bunsen flame so that the flame changes colour.

When students look at the coloured flame through the diffraction grating/spectroscope, they should see a set of coloured lines − the line spectrum of the metal in the salt. They may find it hard to see the lines. If they are using a spectroscope, check that they are looking through the eyepiece and pointing the spectroscope at the light source.

Repeat if students are sharing the spectroscopes or diffraction gratings.

Use a clean flame test wire and fresh distilled water for different salts.

Model of expanding Universe

See worksheet p1_05 activity 3.

Health and Safety Notes

Students must not look directly at the Sun or other bright light sources such as naked bulbs.

Students must observe the flame tests from at least 2 metres away. Then they need not wear safety glasses, which would interfere with their observations.

Ensure that chemicals are handled by the teacher/technician only, in accordance with any COSHH regulations. If you are a member of CLEAPSS, have Hazcards available.



p1_05 The expanding Universe

1 Moving source, changing wavelength

Watch the demonstration showing how the waves on the oscilloscope screen change as the pitch of a note changes.

Answer these questions. Use page 214 of the Student Book to help.

1 a) When the note is high pitched, is the wavelength long or short? ……………………

b) When the note is low pitched, is the wavelength long or short? …………………….

2 Complete these sentences using these words. You may use them more than once.

bluer higher lower redder shorter

a) The wavelength of a sound wave from a source moving away from us is stretched.

This means the wavelength is longer so the pitch is ………………………. .

b) The wavelength of a sound wave from a source moving towards us is squashed.

This means the wavelength is …………………… so the pitch is ………………….

The next sentences are about light – red light has a longer wavelength than blue light.

c) The wavelength of a light wave from a star moving away from us is stretched.

This means the wavelength is longer so the colour of its light is ………………….

d) The wavelength of a light wave from a star moving towards us is squashed.

This means the wavelength is ……………… so the colour of its light is ………….

p1_05 The expanding Universe continued


2 Redshift

You can tell which direction and how fast a star is moving, by looking at its light spectrum.

Light shifts to the red end of the spectrum if the source moves away us.

Light shifts to the blue end of the spectrum if the source moves towards us.

The faster the light source moves, the bigger the redshift or ‘blueshift’. The spectra below are of light coming from different stars. One is from a star that isn’t moving relative to us.

1 For each spectrum, write down:

a) if the spectrum is redshifted or blueshifted

b) if the star is moving towards or away from us.

2 State which star is moving fastest relative to us.

3 A model for the expanding Universe

Work in small groups for this activity, or watch your teacher demonstrate.

Collect an uninflated balloon and draw one dot on its surface, to represent our galaxy.

Draw more dots, at distances of 1 cm, 2 cm and 3 cm from our galaxy.

Blow up the balloon slowly until it is about half inflated, and measure distance of these dots from our galaxy. Record your results.

Blow up the balloon more until it is fully inflated, and measure the distance again from our galaxy to same three dots. Record your results.

1 Describe how the separation of the dots changes when the balloon inflates.

2 Which dots move away from our galaxy at a faster rate as the balloon is inflated?

3 Describe similarities and differences between the balloon model and the expansion of the Universe.



p1_06 The Big Bang

1 How it all began

Make a timeline that runs from 14 thousand million years ago to present time. Use the information below to add events to your timeline. You may be able to find more things to add.

The Universe formed about 14 thousand million years ago. About 2 thousand million years later our galaxy, the Milky Way, formed.

The Sun formed 5 thousand million years ago at the centre of a huge swirling cloud of gas.

We believe that the Earth is about 4.5 thousand million years old. The oldest fossils of living organisms are about 4 thousand million years old. Dinosaurs began to populate the Earth about 230 million years ago, and modern humans evolved about 250 000 years ago.

2 Evidence for these ideas

1 Write down how you can tell how old these different objects are:

a) a building …………………………………………………………………………………….

…………………………………………………………………………………………………

b) a tree that has fallen down …………………………………………………………………

…………………………………………………………………………………………………

c) a loaf of bread ……………………………………………………………………………….

…………………………………………………………………………………………………

In each case, evidence, is needed. This might include knowing the age of other similar objects, or looking at changes that have taken place.

Some methods of determining age are very reliable. For example, changes that occur in radioactive rocks are used to ‘date’ rocks accurately. These readings have been repeated by different scientists.

Some sources of evidence are not good enough on their own to get a precise date. However, if there are several pieces of evidence that suggest the same age, we become more certain that we can trust these results.

2 Use the items of evidence below to estimate the age of the Earth.

A Fossils of bacteria that lived on Earth nearly 3.5 thousand million years ago have been discovered.

B Crystals have been found that formed on Earth 4.3 thousand million years ago.

C Rocks on the Moon are 4.4 to 4.5 thousand million years old.

D Meteorites in the solar system are 4.7 thousand million years old.

E Rocks aged 3.5 thousand million years old have been found on each of Earth’s continents.

Explain how you used the evidence to come to a conclusion for the age for the Earth.

p1_06 The Big Bang continued


3 The future of the Universe

No one knows what will happen to the Universe in the next few billion years. It depends whether outward-acting forces from the Big Bang which caused expansion are matched by the attractive forces of gravity pulling the matter inwards.

To calculate the effect of gravity in the Universe we need to know the mass of the Universe. To calculate the mass of the Universe, we need to know its density and volume.

Scientists are making measurements to calculate the average density in the region of the Universe near Earth. These will be used to calculate the total mass of the Universe, and so the gravitational forces in it.

The ‘critical density’ is the density for which the outward and inward forces are balanced.

1 For each of the statements below, say whether they indicate that the Universe will shrink, will reach a fixed size, or will keep expanding.

A The density of the Universe is below the critical value.

B The density of the Universe equals the critical value.

C the density of the Universe is above the critical value.

D Gravity balances the forces causing expansion.

E Gravity is weaker than the forces causing expansion.

F Gravity is stronger than the forces causing expansion.

2 Identify two problems that scientists must overcome when making measurements of

the average density of the Universe.

Use your Student Book and the internet for more information.



p1_07 Rocks on Earth

1 Fast and slow changes

These headlines are about events that can change the Earth’s landscape. Write all the events that they describe in the table, in order of the timescale in which they occur. The first has been done for you.

Volcano stops erupting one month after it started

2 million-year-old fossil of early human discovered in Africa

An earthquake earlier today has devastated the surrounding area

Last night’s mudslide completely changes the local landscape

New volcanic island has taken four years to reach its current size

New research shows the English Channel formed over thousands of years, after major

flooding when a massive glacier melted

Fold mountains took several millions of years to form completely

say scientists

Over decades, walkers have eroded parts of the hills in the Lake District

Retreating glaciers take hundreds of years to melt

Event Timescale

earthquake

day

p1_07 Rocks on Earth continued


2 What changes tell us about rock processes

Rock processes can result in new rocks forming or existing rocks breaking down.

The series of pictures shows a cross-section through a landscape. The same landscape is shown over a period of several million years, with each picture about a few million years later than the one before.

1 Label each diagram to show where new rocks are forming and where existing rocks are breaking down.

2 Write a sentence for each diagram, explaining whether erosion or sedimentation is happening at each of the different stages, giving as much detail as you can.

3 Explain what needs to happen to avoid the continents being worn down to sea level.

p1_07 Rocks on Earth continued


3 Dating rocks

Scientists use several methods to date rocks.

1 Write down one advantage and one disadvantage of each of the above methods of dating rocks.

To find the age of the Earth, scientists need to know the age of the oldest rocks on Earth. They need to date the rocks from the very lowest layers because these should be the oldest rocks.

The rock cycle continuously recycles rocks and rock fragments, so it is very difficult to find rocks that were in their present form when the Earth began. However, samples of rocks 3500 million years old have been found on all the Earth’s continents. Single crystals of rocks up to 4500 million years old have also been found. These were dated using radioactive dating methods.

Rocks on the Moon are not recycled as rapidly as rocks on Earth. The oldest rock samples collected from the highlands of the Moon are about 4500 million years old, and the youngest rocks collected from lowlands are about 3200 million years old.

Meteorites that have landed on the Earth have been dated as at least 4550 million years old.

2 Explain why we think the Earth is about 4500 million years old. Include at least two

pieces of evidence in your answer.

3 Why is this age of the Earth likely to be a minimum age?

4 Explain why radioactive dating is the best method to use to find the age of the Earth.

If rocks in a region contain fossils, the rocks must have formed when the

fossils were living organisms. If scientists know the age of the fossils from

other studies, this method is a straightforward way of dating rocks in a region.

This method cannot be used to date rocks formed before there were living

organisms on Earth.

Scientists can examine the structure of the rocks in different regions by

studying the landscape or by taking core samples by drilling a deep hole and

then looking at the section of rock it removes. The layers of rocks formed at

different times, with newer rocks lying on top of older rocks. This method is

fairly straightforward, giving a rough idea of the sequence of the formation of

rocks in a region, but it does not give the true age of the rocks.

The true age of rocks can be found using radioactive dating. Rocks contain

many different elements, some of which are radioactive. Over time, nuclei of

radioactive elements emit radiation and change into nuclei of different

elements. For example, some forms of potassium are radioactive and change

to argon. This is called radioactive decay. We know how quickly different

decays take place. If newly formed rock includes potassium atoms, for

example, after 1250 million years half of this potassium will change to argon.

Geologists can measure the proportion of argon and potassium in rocks they

find today, and this enables them to work out how long it is since the rock

formed. This is a very accurate method of dating rocks, so long as they contain radioactive elements.



p1_08 Continental drift

1 Moving continents

Use page 220 of your Student Book to help with this activity.

1 Add arrows to the diagram to show which way each continent has moved during the last 200 million years.

2 Which continents appear to have moved more than others?

……………………………………………………………………………………………………

Wegener used clues from fossil records and rock types to back up his idea that some continents had once been joined together.

3 Spread out the pieces of a jigsaw puzzle. Look for clues from the images on them to join them together. Describe two ways you could tell which pieces fitted together.

…………………………………………………………………………………………………

…………………………………………………………………………………………………

4 Describe two decisions you had to make before fitting the pieces of the jigsaw puzzle together, which were similar to Wegener’s work in seeing how land masses were once joined.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

p1_08 Continental drift continued


2 Who believes in continental drift?

Many scientists found it hard to accept the idea of continental drift. They had a response or an alternative idea for each of Wegener’s ideas. Some statements are shown below, which can be grouped as follows:

made by Wegener (W) made by geologists who explained his evidence in other ways (G) possible explanations or descriptions of further evidence that is needed (E).

Sort the statements, putting each one into one of the three groups W (Wegener), G (geologist) or E (explanation/evidence).

Then choose one statement from each of the three groups that discusses the same point. Write these out or stick them down as a group of three

The continents are moving We can’t see

continents moving

If the continents take millions of years to move, it would be

hard to detect

Continents may have moved because

of tidal movement

There is no evidence that tides are strong

enough to move continents

Tides can’t move continents but

processes inside the Earth could

Continents are shaped like jigsaw puzzle pieces that could be joined together

Continents have always been the same

shape and don’t fit exactly together

We need more evidence to prove continents were once joined

together

Fossils that lived in cold climates can also

be found in continents that have hot climates

The cold climate was more widespread

in the past

Several continents were clustered near the South

Pole and have now spread across the Earth

Mountains made from the same rock types occur on separate

continents

Mountains formed in the same way all over the Earth

as the Earth cooled and the crust wrinkled

The same types of mountain are only

found in some places on Earth

The same animals occur on separate continents because the continents

moved apart

The same animals occur on separate continents because all continents

were linked by land bridges that have now vanished

There is no evidence of land bridges but they can’t vanish

completely



p1_09 Tectonic plates

1 What happens when tectonic plates move?

You are going to model the movement of tectonic plates and match the movements with the effects they cause.

Collect two sheets of thick paper or card and lay these next to each other. They represent two tectonic plates. The plate boundary is where the two sheets meet.

Earthquakes

Slide one tectonic plate along the edge of the other. This causes an earthquake

1 What could happen to a building near the plate boundary during the earthquake?

……………………………………………………………………………………………………

2 Why are buildings in the middle of a tectonic plate much less likely to be damaged?

……………………………………………………………………………………………………

Volcanoes

Pull one tectonic plate away from the other tectonic plate. This can cause a volcano.

3 What happens at the boundary if there is semi-liquid rock under both the plates?

……………………………………………………………………………………………………

4 Explain why volcanoes are much less likely to occur in the middle of a tectonic plate.

……………………………………………………………………………………………………

Fold mountains

Hold one tectonic plate firmly in place and push the other plate towards it. One plate is likely to crumple at the plate boundary or push under the other plate. This crumpling is how some mountains form.

5 Why are mountain ridges mainly found at plate boundaries?

……………………………………………………………………………………………………

……………………………………………………………………………………………………

p1_09 Tectonic plates continued


2 Plate tectonics around the world

Moving tectonic plates have a very big impact in certain places around the world.

Use the internet to look at a world map that shows the position of major volcanoes. Mark the position of these in red on the map below.

Use the internet to look at a world map that shows the position of major mountain ranges. Mark the position of these in green on the map.

Use the internet to look at a world map that shows the position of mid-ocean ridges. Mark the position of these in blue on the map.

1 Explain how you can use your map to state which tectonic plates are:

a) moving closer together

b) moving further apart.

p1_09 Tectonic plates continued


3 The rock cycle and tectonic plates

This diagram below shows the stages in the rock cycle. The rock cycle could not take place without plate tectonics.

Draw your own version of the rock cycle, identifying every point at which plate tectonics are involved.

The table contains information you can use to link the movement of tectonic plates to the rock cycle.

At a mid-ocean ridge, tectonic plates move apart and magma comes to the surface forming new igneous rock

At a subduction zone, tectonic plates move together and one tectonic plate is dragged underneath another.

Sediments and sedimentary rocks on the surface at the subduction zone are dragged under with the tectonic plate.

High pressure and temperature underground change sedimentary rock into metamorphic rock.

Metamorphic rock melts underground forming magma.

Magma is forced to the surface in volcanoes near the subduction plate boundary (where one tectonic plate moves under another).

At the surface, magma cools to become igneous rock.

Mountains formed on land as two tectonic plates move together are made from igneous rock.



p1_10 Earthquake waves

1 Models of the Earth

1 Label the diagram using the words:

crust inner core

mantle outer core

2 Complete the sentences below. Use these words in the gaps:

crust inner core liquid

mantle outer core solid

At the centre of the Earth is the ……………………., which is solid / semi-liquid / liquid.

The next layer out is the ……………………., which is solid / semi-liquid / liquid.

The next layer out is the ……………………., which is solid / semi-liquid / liquid.

The outside layer of the Earth is the ……………………., which is solid / semi-liquid / liquid.

3 You are now going to compare the structure of the Earth with two models, to identify the properties of the different layers.

a) An apple has a skin, flesh and a core.

Write down three ways in which the apple’s structure is similar to the Earth’s structure.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

Write down two ways in which the apple’s structure differs from the Earth’s structure.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

b) An egg has a shell, a white and a yolk.

Write down three ways in which the egg’s structure is similar to the Earth’s structure.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

Write down two ways in which the egg’s structure differs from the Earth’s structure.

……………………………………………………………………………………………………

……………………………………………………………………………………………………

p1_10 Earthquake waves continued


2 Detecting earthquakes

The diagram shows earthquake monitoring stations set up around the world – A, B … . The seismologists at these monitoring stations have detected seismic waves, and now are trying to find out where the earthquake originated.

A detected strong waves at 5.10 and 5.12

B detected very strong waves at 5.00 and 5.01

C detected strong waves at 5.11 and 5.13

D detected weak waves at 5.25 and very weak

waves at 5.30

E detected very weak waves at 5.30

F detected weak waves at 5.40

1 Which station was closest to the earthquake? How could you tell?

2 Which station was furthest from the earthquake? How could you tell?

3 Why were waves detected at different times at the stations A, B, C and D?

4 Why was only one type of wave detected at stations E and F? Which type was detected?

5 Use the information given to mark on the diagram where you think the earthquake occurred.

p1_10 Earthquake waves continued


3 Longitudinal and transverse seismic waves

Your teacher will demonstrate longitudinal waves and transverse waves travelling along a slinky spring. Observe the shape of each type of wave and sketch it.

Time how long it takes one disturbance to travel along the spring for each type of wave. Note down the results.

Your teacher will put a metre rule next to the spring. Watch to see which type of wave touches or disturbs the ruler most.

1 a) Which type of wave travelled quickest along the slinky spring?

b) P seismic waves travel faster than S seismic waves. P-waves are longitudinal waves and S-waves are transverse waves. Do your results match the behaviour of P- and S-waves?

2 a) Which type of wave disturbed the ruler most?

b) P-waves are longitudinal waves, which travel as compressions (pressure waves) through the Earth. S-waves are transverse waves, which cause a lot of shaking. Use your observations to explain why S-waves are more damaging than P-waves.

3 Explain how the following ideas could help in protecting buildings and people from an earthquake:

a) Designing an earthquake-warning system to be very sensitive to P-waves

b) Surrounding a building with a very large trench filled with water or another liquid.



p1_11 Measuring wave speed

P Using a ripple tank

Objectives

In this activity you will:

collect information to calculate how fast a wave travels


tank at least 30 cm long • stopclock • 30 cm ruler • 15 cm ruler

Method

1 Lay a 30 cm ruler along the tank. Mark the start and finish of a 30 cm length, and then remove the ruler.

2 Pour in a small amount of water and measure how deep the water is (between 0.5 cm and 1 cm is suitable).

3 Use a ‘dipper’ to create a ripple at the ‘start’ mark – the edge of a 15 cm ruler works well.

4 Time how long it takes the ripple to travel the 30 cm. You may need to practise this.

5 Repeat your experiment three times.

6 Add more water to the tank so the water is about 0.5 cm deeper.

7 Repeat your readings.

8 Repeat the experiment for four different depths of water.

Results

Water depth (cm)

Time to travel 30 cm Average time to travel 30 cm (s)

Wave speed (cm/s) 1st reading

(s) 2nd reading (s)

3rd reading (s)

Questions

1 Complete the ‘Average time’ column of the table by calculating the average reading for

each water depth.

2 Calculate the speed of the wave for each depth of water. Use the equation:

distance travelledwave speed

time taken

3 How does the speed of the wave in water change as the water gets deeper?

…………………………………………………………………………………………………......



p1_11 What a wave is

1 Waves in a ripple tank

Watch your teacher demonstrate waves travelling in a ripple tank. Tick off each of the following as you see it:

The wave carries energy across the tank, but water remains in the same place. ゴ

The wave travels as a series of crests and troughs. ゴ

The wavelength is the distance between crests. ゴ

The wavelength is shorter when more waves are created each second. ゴ

You can measure the speed of waves in a tray of water yourself, using the Practical sheet.

2 Waves on an oscilloscope

Watch the demonstration. Sound waves are converted into electrical signals and shown on the oscilloscope screen

Sketch the wave you see on the screen. Label the wavelength and the amplitude.

1 For the wave you drew, how many squares on the grid is one wavelength?

2 For the wave you drew, how many squares on the grid is the amplitude?

3 What do you see on the screen when the loudness of the note changes?

4 What stays the same when the loudness changes?

5 What do you see on the screen when the pitch of the note changes?

6 What stays the same when the pitch of the note changes?

p1_11 What a wave is continued


3 Interpreting an oscilloscope trace

An ECG trace is shown below. This is a trace of a person’s heartbeat. Every time the person’s heart beats, an electrical pulse is sent to a machine, which displays it as a peak on an oscilloscope screen.

On this diagram, each square on the x-axis represents 0.2 seconds and each square on the y-axis is 0.5 mV.

1 How many peaks are shown on the trace?

2 a) Write down how many squares there are between two successive peaks.

b) How much time passes between two successive peaks?

c) The pulse rate is the number of heartbeats per minute. What is the patient’s pulse rate?

3 On squared or graph paper, draw a trace from another patient. Their heart is beating at the same rate, but more strongly. Its peak value is 4 mV. Label the axes.

4 On squared or graph paper, draw a trace from a third patient. Their heart is beating faster − the time between peaks is 0.6 seconds. The heart beats as strongly as the first patient’s. Label the axes.

5 Explain why oscilloscopes are useful for monitoring a patient’s condition.

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