P2.1.2 Forces and Motion

P2 Physics

KS4 ADDITIONAL SCIENCEMr D Powell

Mr Powell 2012Index

Connection

• Connect your learning to the content of the lesson

• Share the process by which the learning will actually take place

• Explore the outcomes of the learning, emphasising why this will be beneficial for the learner

Demonstration

• Use formative feedback – Assessment for Learning

• Vary the groupings within the classroom for the purpose of learning – individual; pair; group/team; friendship; teacher selected; single sex; mixed sex

• Offer different ways for the students to demonstrate their understanding

• Allow the students to “show off” their learning

Activation

• Construct problem-solving challenges for the students

• Use a multi-sensory approach – VAK• Promote a language of learning to

enable the students to talk about their progress or obstacles to it

• Learning as an active process, so the students aren’t passive receptors

Consolidation

• Structure active reflection on the lesson content and the process of learning

• Seek transfer between “subjects”• Review the learning from this lesson and

preview the learning for the next• Promote ways in which the students will

remember• A “news broadcast” approach to learning

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P2.1.2 Forces and Motion

a) The acceleration of an object is determined by the resultant force acting on the object and the mass of the object: F = ma

b) The gradient of a distance–time graph represents speed.

c) Calculation of the speed of an object from the gradient of a distance–time graph. (HT)

d) The velocity of an object is its speed in a given direction.

e) The acceleration of an object is given by the equation: a = (v – u)/t

f) The gradient of a velocity–time graph represents acceleration.

g) Calculation of the acceleration of an object from the gradient of a velocity–time graph. (HT)

h) Calculation of the distance travelled by an object from a velocity–time graph. (HT)

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d) Velocities....

Object Est. Velocity m/s

Man

Comet

Concorde

Football

Bullet Train

Snail

Make a table similar to this with and estimate of each objects velocity. Try and order it as fastest first..

A

Bullet Train = 262km/h or 164mph

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d) Velocities....

Object Est. Velocity m/s

Man 10

Comet 55,555

Concorde 666

Football 15

Bullet Train 73

Snail 0.001

Make a table similar to this with and estimate of each objects velocity. Try and order it as fastest first..

A

To convert km/hour to m/s simply x1000/3600

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Fill in the gaps....

• On the following slides you will see completed motion graphs for;

distance – time graphs

• Fill in the gaps in your worksheet and complete the final box on proper graph paper.

A

Distance - Time

A

Distance - Time

A

Distance - Time

A

Distance – Time - NB Nothing removed from this one!

A

Distance - Time

Now try this journey with several stages.... A

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Plot this new graph.....

Now you have seen how a d-t graph is plotted try doing this one yourself and work out the average speed of the car....

Distance (m) 0 1000 2000 3000 4000 5000 6000

Time (s) 0 35 76 130 186 203 235

A

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Distance Time Graphs D

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Plenary Question... DThe fastest moving man-made object was the Helios 2 space probe. It travelled at about 67 km/s (67 000 m/s), which is Mach 203 (not that sound can travel in space).

Space probes can travel so quickly, because there is no air resistance so they do not lose any of their kinetic energy.

The probe Voyager 1 is travelling at 17.5 km/s and has been travelling for around 30 years. Answer the question below and write out your working in your book.

‘How far away is it from Earth now?’

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d) Backwards or Forwards? Aa) Write down a set of instructions for a person to get from point

A to Tesco via two different routes

b) Think about the two routes and describe as fully as you can the differences in speeds and direction of the speed

A1mile

1mile

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d) Vectors? A On this racetrack a car covers 1.029 miles in distance by

covering a circuit in a lap. After 1 lap the car is back to the start and has completed the lap at a constant speed of 30 mph.

However, when we think of the term “velocity” we describe not just the speed but the direction. In this case the “velocity” changes direction all the time. We call it a vector quantity. This feature is important in helping us describe the motion of objects clearly!

Mr Powell 2012Index

Fill in the gaps....

• On the following slides you will see completed motion graphs for;

velocity – time graphs

• Fill in the gaps in your worksheet and complete the final box on proper graph paper.

A

Velocity - Time

A

Velocity - Time

A

Velocity - Time

A

Velocity - Time

A

Velocity - Time

Now try out this journey with multiple parts... A

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e) Acceleration A

at

v

t

uv

A more grown up way to express this is to look at the change in velocity as a Greek “” term over the time period.

We can also use the idea of ;

• v = final velocity• u = initial or starting velocity

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e) Acceleration A

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1.2 Quick Questions DCopy out the questions below and draw a diagram or formulae to help

you explain each one. Make sure you do it all on your own!

1. What is the difference between speed and velocity?

2. What is acceleration and what are its units?

3. What is deceleration? A

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Acceleration and Power D What makes a vehicle good at accelerating? There are two main factors;

weight & brake horse power (BHP or kW). We can compare different cars by excluding the weight i.e. Diving the Power by the Mass to create a Power to Weight ratio.

Write an article explaining the reason for the 0-60 times for these cars referring to the data shown below. Also the idea of how to use it and power to weight ratios to compare any car. (You can use a table if required)

Key words: fair test, variables, power, weight, time, max power, etc...

1 – Saleen S7 Power-to-weight ratio: 0.2540-60 mph: 2.8 secondsTop speed: 235 mph

2 - Porsche Carrera GT Power-to-weight ratio: 0.1980-60 mph: 3.9 secondsTop speed: 205 mph

3 - Ferrari 599 GTB Fiorano Power-to-weight ratio: 0.1660-60 mph: 3.6 secondsTop speed: 205 mph

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Tortoise & Hare! D

“Yes Mr Hare you were right he is on steroids!”

In your books sketch a quick graph of a race in which a tortoise and a hare cover the same distance. The tortoise wins the race but the hare has a quicker top speed in parts of the race. You axis should be (0s to 100s and 0m to 1000m)

Try and justify your answer with some maths!

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Distance Travelled.... A We can work out a really cool thing by working out the area under a v-t

graph. If we add it all up it actually means the distance covered!

Make a sketch copy of the diagram and work this out for each of the journeys. (with full working)

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Deceleration in context of a car braking.... D This graph is a simple

example of a car travelling at 20m/s for a time of 10 seconds.

Then the car brakes / slows down / decelerates at a constant rate till it stops. This takes 5s.

Use the acceleration formula to work out the deceleration. Then write a sentence and draw a sketch graph to match

at

v

t

uv

22 4/45

/200

mssms

sm

t

uv

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Energy = Power x Time

Energy = 145W x 1 hour

Energy = 145W x 3600s

E = 145J/s x 3600s

E = 522000J

E = 522kJ

3 Marks

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Acceleration Questions...

Copy out the each question, sketch a velocity-time graph and answer in full with your working;

1. A car is travelling at a constant speed of 10m/s for a time of 5s. It then decelerates to a halt in a time of 5 seconds. What is the deceleration?

2. A car is travelling at a constant speed of 5m/s for a time of 2s. It then decelerates to a halt in a time of 2 seconds. What is the deceleration?

3. A fighter jet is on a runway and then takes off. Air traffic control record Its velocity as 250 m/s and the time from take off as 10 seconds. What is the acceleration of the plane?

4. A basket ball has an acceleration of 10ms-2 when dropped from a window. The time of flight is 5 seconds. What is the velocity of the ball just before it hits the ground (ignore air resistance)?

at

v

t

uv

v = final velocityu = initial velocitya = accelerationt = time

1. 2ms-2

2. 2.5ms-2

3. 25ms-2

4. 50ms-1

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1.3 Velocity –Time II D

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Maths Skills....

Width Height Area

1

2

3

4

Look at these shapes to the right, can you work out their areas?

A

1

2

4

3

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Maths Skills....

Width Height Area

1 3 4 6

2 2 6 6

3 2 4 8

4 3 3 9

Look at these shapes to the right, can you work out their areas?

1

2

4

3

A

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Distance Travelled....

So if you apply the Maths properly you can find out how far an object travels by working out the area underneath a graph.

Can you do it for this one....?

21

mArea

mmArea

smsmArea

ssmssmsArea

250

50200

5202

1200

1015202

11020

1

11

A

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Cyclist accelerated from 0m/s to 8m/s in a time of 40s

8ms-1 /40m = 0.2ms-2

(8ms-1 x 40s) /2 = 160m

40ms-1 /20s = 2ms-2

(40ms-1 x20s)/2 = 400m

(400ms-1 x10s) = 400m

Velocity Time II D

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Acceleration.... D

Consolidate – How can you explain these things...a) The acceleration of an object is determined by the resultant force acting on the object and the mass of the object: F = ma

b) The gradient of a distance–time graph represents speed.

c) Calculation of the speed of an object from the gradient of a distance–time graph. (HT)

d) The velocity of an object is its speed in a given direction.

e) The acceleration of an object is given by the equation: a = (v – u)/t

f) The gradient of a velocity–time graph represents acceleration.

g) Calculation of the acceleration of an object from the gradient of a velocity–time graph. (HT)

h) Calculation of the distance travelled by an object from a velocity–time graph. (HT)

P2.1.2 Forces and Motion