ENERGY 1

Energy

Student book

In this module you will learn more about the nature of energy. Initially you will carry out an investigation on Solar Energy and Hot Cars. Then you will examine some other forms of energy. Finally you will try to understand the idea of energy and how it changes.

ENERGY 2

ENERGY - ACTING RESPONSIBLY

Erica said that if she could buy an electric car this would help reduce the use of fossil fuels. But Peter said that it would not reduce the use of fossil fuels. Is he right?

Greg said he got his energy from sleeping. Barry said he got his energy from the food he ate. Who is correct?

When Harry went skiing near Mt Kosciusko, he still put on a sun screen cream. Jack did not use a sun screen. He said it was too cold to get sun burnt? Will anything happen to Harry and Jack?

John said that if he has white coloured roof tiles on his house it will help keep it cool in summer. Barry said he preferred chocolate coloured roof tiles because this colour stopped the heat passing through the tiles.

Alice uses reverse cycle air conditioning in her house in winter to warm the house because it was cheaper. Stephen said he uses an oil heater. Who is doing their best for the environment?

Susan said that the Earth appears to be heating up due to the greenhouse effect. Mary said there was a hole in the ozone layer and this was causing the Earth to heat up. What do you think?

What are your thoughts about the following questions?

ENERGY 3

Energy Flow Diagrams

Efficiency of Energy Transformations

What is Energy? - Revisited

Chemical Energy **

Mechanical Energy

*

Ultra violet Energy

**

Electrical Energy **

Wind Energy **

Solar Energy *

ENERGY

What is Energy? - Discussion

Solar Energy - Discussion

Hot Cars Investigation *

Theory - Discussion

Energy Flow Diagram - Discussion

OTHER INVESTIGATIONSChoice (do 2 or 3)

Energymodule overview

YOU ARE HERE

ENERGY 4

What is energy?

How often have you heard the following expressions?

• I am all out of energy.

• There is an energy crisis.

• This music is high energy dance music.

@ How many other expressions about energy can you add to this list?

‘Energy’ has two parts. They come from the Greek words en and ergon.

What do they mean?

Explain why were they chosen to form the word energy.

(HINT: Try a dictionary)

@ What you think the word energy means? Write down your ideas. There is no right or wrong answer.

Your answers will be collected and given out at the end of the Module for you to review.

ENERGY 5The Feagvk Jiuhdfm

Solar Energy - DiscussionToday we make a lot of use of solar energy, or solar power as it is sometimes called.

• What devices do you have in your house that use solar energy?

• What other devices use solar energy?

• Is solar energy always good?

• What are some problems related to solar energy?

The next page shows one of the serious effects of solar energy.

ENERGY 5

ENERGY 6

TUESDAY APRIL 9 2002

2 y.o. left alone for thirty minutesTHE police are investigating the death of a 2 year old girl. She was spotted by passers-by inside a locked car.

She appeared to be unconscious when she was discovered. The black car had been locked with the windows down by about 4 centimetres.

The car was in the full sun when the child was found. It appears it was parked in the shade, but the Sun had moved and it was no longer in the shade.

The temperature yesterday reached 28˚C. However, the temperature inside the car could have reached 50˚C.

The manager of the shopping centre broke the window of the car to remove the child.

The ambulance was called and first aid applied. However the girl was dead on arrival at the hospital.

“The day was not very warm, but the car was surprisingly hot inside,” said the manager of the shopping centre.

A police spokesman said that this was the second incident like this in the last week. The previous incident resulted in a young boy going to hospital.

“Fortunately he recovered fairly quickly.”

A government spokesperson said that legislation was being considered to make it illegal to leave children in locked cars.

The Automoblile Club warned that there was no

safe time to leave children locked in vehicles. Leaving the windows partly open made very little difference.

Comment, page 16

Established 1927

The Feagvk Jiuhdfm

ENERGY 7

Hot CarsThe people who are going to plan legislation to help prevent incidents like that described in the newspaper need to better understand what is happening. They need to understand questions such as

• Why did the car get so hot on such a mild day?

• Would the colour of the car have had an effect on the death of the child?

• What effect did the partly closed windows have?

• How quickly did the temperature in the car change?

• Would tinted windows have helped? • Would the car have got hot if it was in

the shade?

You could provide the legislators with this understanding by carrying out relevant investigations.

ENERGY 8

NOTE TO TEACHERAn Investigation Planner is provided as a resource sheet. It is flexible enough to be used with each investigation.

Hot Cars - Investigation *

There are several aspects of the Hot Cars problem that you could investigate scientifically. Your group could choose one of the following variables to investigate.

• You could investigate the effect of the colour of the car.

• You could investigate the effect of having windows open or closed.

• You could investigate the effect of having tinting on the windows.

• You could investigate the effect of being in the shade or in the sun.

ENERGY 9

Hot Cars - Investigation Question

Hot Cars - Investigation Planning

Get a copy of the Investigation Planner from the Resource File.

Choose which of the variables you are going to investigate.

@ What are you going to investigate?

Enter this on the Planner in the form of a question.

Investigation Question

@ What do you think will happen? Explain why.

Enter your prediction on the Planner.

Before you can complete the planner you need to have in mind what approaches and techniques you will use in the investigation. Some techniques follow on the next page.

Prediction

ENERGY 10

Hot Cars - Investigation Techniques

If you are investigating the effect of being in the shade or in the sun on the rise in temperature, you could use some thin card. Fold it into the shape of envelopes. Place a thermometer inside each. Expose them in the sunlight and in the shade.

If you are investigating the effect of having tinting on the window on the rise in temperature, you could use inverted transparent ‘take-away’ trays covered with tinting material. You may be able to get off cuts from a car tinting firm. Otherwise you could use clear and grey cellophane over the trays.

If you are investigating the effect of having windows open or closed, or even partly open, on the rise in temperature, you could use transparent (remember Light module) ‘take-away’ trays. Cut various sized windows in the sides. Place a thermometer inside. Then expose each to the sunlight.

If you are investigating the effect of colour on the rise in temperature, you could get different coloured sheets of thin card. Fold them into identical envelopes (to control the variable of area). Place a thermometer inside each. Then expose each to sunlight.

ENERGY 11

TEACHER CHECK

Hot Cars - Investigation Planning@ Which variable are you going to change?

Enter this on the Investigation Planner.

@ Which variable are you going to measure?Enter this on the Planner.

@ Which variables are you going to keep the same?Enter these on the Planner.

@ How will you make it a fair test?Enter this on the Planner.

@ What equipment will you need?Enter this on the Planner.

@ What are the steps that you will carry outwhen you do the Investigation?

Enter this is your planner.

TEACHER CHECK• Check with your teacher that your investigation is safe to

carry out.

Dependent Variable

Controlled Variables

Independent Variable

Equipment needed

Fair test

Procedure

ENERGY 12

Hot Cars - Investigation ResultsCarry out the investigations

What happened? Complete the Results sections in your Investigation Planner.

@ Describe your observations and records you results in a table on the Investigation Planner.

@ What do your results tell you about a car parked in the sun? Are there any patterns or trends in your temperature results? Enter this on the Planner.

@ Try to explain the pattern or trend in the temperature changes. Try to use some science ideas to help explain what happened.

@ What did you find out about the Hot Car problem you investigated? Was the outcome different from your prediction? Explain.

@ What difficulties did you experience in doing this investigation?

@ How could you improve this investigation e.g. fairness, accuracy?

Results

Conclusion

ENERGY 13

Hot Cars - Investigation Report@ Your task now is to write a report to the Minister for the Police detailing the outcomes of your investigation.

Describe

• the evidence you have used to reach your conclusion,

• recommendations to the Minister about any laws that should be drawn up based on the results of your investigation, and

• any other research that should be undertaken.

Action

ENERGY 14

Hot Cars - What’s Happening HereRead the following:

Solar energy comes from the Sun.

It travels from the Sun to the Earth’s surface mainly as visible light, infra red light and some ultra violet.

Visible light, infra red and ultra violet are all forms of electromagnetic wave energy (these were introduced in the Light Module).

Visible light is what we can see with our eyes and can been seen by cameras. It also makes us feel warm if it gets absorbed by our skin.

Infra red cannot be seen with our eyes. It can also make things warm when it is absorbed.

Ultra violet has trouble getting through the Earth’s atmosphere. However the small amount that does get through is very powerful and causes sunburn and skin cancer.

When the electromagnetic wave energy reaches the car, three things can happen. It can be reflected, transmitted or absorbed.

Transmitted

Absorbed

Electromagnetic wave energy

reflected

ENERGY 15

Hot Cars - What’s Happening HereSome of the electromagnetic wave energy can be reflected off the glass windows and off the painted surface of the car.

Some of the electromagnetic waves energy can be transmitted through the glass into the car.

Some of the electromagnetic waves energy can be absorbed by the surface of the car, or by the insides of the car making it hot.

It is only the electromagnetic wave energy which gets into the car and is absorbed that produces heat energy.

@ What are the three types of electromagnetic energy in Solar energy?

@ Describe the three things that can happen to the electromagnetic wave energy from the Sun when it reaches the car.

@ Why did the electromagnetic energy from the Sun cause the inside of the car to get warmer?

The above energy flow diagram shows that energy from the Sun arrives and is changed into heat energy when it is absorbed by something.

ENERGY FLOW DIAGRAM

Absorbed

energy becomes Heat energy

Electromagnetic wave energy (visible light, infra red and ultra violet) transmitted through glass.

Some energy is reflected

ENERGY FLOW DIAGRAM