KS3 Science Forces 1 - Rastrick High School...2020/12/07 · KS3 Science Forces 1 Home Learning...

KS3 Science

Forces 1Home Learning booklet with answers

Name: _____________________________

Class: _____________________________

Teacher: ___________________________

In this topic you will learn about:

• Speed and Relative motion

• Distance time graphs

• Different types of forces

• Weight, Mass and Gravity

Practical Skills:

• Assessed Enquiry – Speed down a ramp

This will prepare you for:

• GCSE physics topic ‘Forces A & Forces B’

This topic has links to

• Y8 forces

Maths in science:

• Rearranging Equations

• Plotting Graphs

Key Words:

Speed

Acceleration

Deceleration

Relative Motion

Force

Stationary

Constant Motion

Weight

Mass

Gravity

Air resistance

Reaction force

Upthrust

Watch this LOOM video:

https://www.loom.com/share/5a3e7a59f4dd466d9e6ca5757f8fdb8c

Contents:

Booklet Expectations:

The booklet is your responsibility to look after and keep tidy.

You are expected to bring the booklet to every lesson with that class teacher.

Any corrections / self assessment to be completed in green pen, as indicated by your class teacher – Or when you see the ‘feedback & assessment’ logo

Any response to marking and literacy codes to be completed in green pen.

Any diagrams are to be drawn in pencil, graphs using a pencil and ruler etc.

All activities are to be completed, including homework, to the best of your ability, and corrected where needed.

When reading through the notes, you are expected to highlight any words you do not understand, then write their definitions on the glossary pages at the back of the booklet.

Lesson 1: Understanding speed

Lesson 2: Distance time graphs

Lesson 3: Exploring Journeys on Distance time graphs

Lesson 4: Assessed Enquiry

Investigating motion of a car on a ramp

Lesson 5: Relative Motion

Lesson 6: Different Forces

Lesson 7: Mass, Weight and Gravity

Revision

Student made Glossary

ANSWERS AT BACK OF BOOKLET


In and On: Write down any questions you have about speed

Learning outcomes:

• List the factors involved in defining speed.

• Describe a simple method to measure speed

• Use and apply the speed formula.

How far could you travel going 60mph and 50 mph in…

a) 1 hour?

b) 2 Hours?

c) 5 Hours?

d) 30 minutes?

Speed is ____________________________________________

In science the units we use are

Distance – meters (m)

Time – Seconds (s)

Speed – Meters per second (m/s)

Use the formula triangle above to calculate speed:

a) 100 m in 20 seconds

b) 48 m in 4 seconds

c) 57 m in 3 seconds

d) 3 km in 100 seconds

e) 1 km in 1 minute

f) 350 km in 5 hours

Challenge:

Calculate distance travelled in km

when speed is 50m/s and the car

has been travelling for 3 hours.

Practical:Aim: calculate the speed of various ways to move

Imagine a normal journey across a town that is 15 km across. The car

sets off at 9.00 am and arrives at 11.00 am. During the journey the

car reaches a highest speed of 50 km/h but has to slow down for

traffic and stop several times at junctions.

a) Work out the overall average speed for the journey.

b) Explain why the average speed is so much lower than the highest

speed.

c) Two cyclists, Victoria and Laura, also set off at 9.00 am and head

for the same destination as the car. Victoria takes the same route

as the car and arrives at 10.30 am. Laura takes the ring road,

which is a distance of 22 km, and arrives at 10.15 am. Work out

the average speeds of the two cyclists.

d) Suggest reasons why Laura arrived first despite taking the longer

route.

Challenge task: Average speedsRead the information & complete the questions.

Additional notes:

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Learning outcomes review:




Key Vocab:

Speed limits are enforced in the UK.

Write down reasons why these are important.

Why can you go faster on the motorway than in an urban area?


In and On: Look at the picture of the graph.

Discuss with a partner what you think this

represents.

Learning outcomes:

• Gather relevant data to describe a journey.

• Use the conventions of a distance–time graph.

• Display the data on a distance–time graph.

A journey can be represented using a distance time graph.

The graph shows a cyclists journey.

1) What units could measure the cyclists speed?

2) How far did they travel in the first 6 seconds?

3) What was the cyclists speed?

4) Sketch another line to show the journey of a

cyclist who is travelling at half the speed.

For each graph below – write a few words to describe the speed of each

Suggestions: Constant speed, stationary, accelerating, decelerating.

Challenge: What about the direction of the movement?

Task 1: Write a brief description of each journey shown on the graphs

a) ______________________________________________________

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b) _______________________________________________________

_________________________________________________________

c) _______________________________________________________

_________________________________________________________

d) _______________________________________________________

_________________________________________________________

Time (min) 0 10 15 20 30 40 50 60 70 80 90

Distance travelled by car (km) 0 10 10 15 20 40 60 65 70 75 80

Distance travelled by train (km) 0 20 30 40 40 60 80 80 80 80 80

Task 2: On the same graph, plot a distance time graph for each journey

From your graph, answer these questions:

Identify the times when:

i) the car was not moving __________________

ii) the train was not moving. __________________

What was the total journey time for:

i) the car ___________________

ii) the train? ___________________

Challenge questions:

Calculate the fastest speed in km/h achieved by each mode of transport.

Calculate the average speed in km/h over the entire journey for each mode of

transport.

Suggest why one mode of transport has a quicker journey time than the other.

Plenary: Complete the sentences:

A horizontal line on a distance-time graph shows

________________________.

The steeper the line on the graph, _______________________.

A curved line shows ____________________________.

Options: Faster the speed / Object is stationary / acceleration or deceleration

Additional notes:

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Key Vocab:




Lesson 3: Exploring journeys on distance-time graphs

In and On: Solve the anagrams:

Deeps: _________ Ratgiend: _________ Veeraag: ___________

Learning outcomes:

• Interpret distance–time graphs to learn about the journeys represented.

• Relate distance–time graphs to situations & describe what they show.

Task 1: Work out the missing values, use the triangle to help

Distance = 130 milesSpeed = ? mphTime = 2 hours

Distance = ? KmSpeed = 13 km/hTime = 3 hours

3. Distance = 48 mSpeed = 4 m/sTime = ? Seconds

Distance = 60 milesSpeed = ? mphTime = 30 minutes

Distance = 20 kmSpeed = ? km/hTime = 15 minutes

Task 2: Can you match the pictures with their respective graphs?

Challenge: Explain your choices:

Acceleration

On a distance–time graph, a _____

slope shows that an object is travelling

_______ than an object with a shallow

slope. If the object rapidly _________,

the slope of the line will change

rapidly. However, if the change in

speed is more gradual, the _______

will change more gradually.

Which object has the fastest starting speed? _____

Which object has the fastest final speed? _____

Task 3: Write a short story describing each graph:

_________________

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Task 4: Complete the following questions: The distance–time graph shows the journey of a tennis ball rolling down a ramp and across the floor.

a) Label the curve to show:

i) where the ball is travelling fastest

ii) where the ball is accelerating

iii) where the ball is slowing down

iv) where the ball is stationary.

b) Explain why the ball speeds up for part of its journey and slows down for part of its journey.

________________________

________________________

Imagine it took 10 seconds from the moment the ball was released to when it finally came to rest. If the motion was videoed and the recording was stopped after each second, we would see the position of the ball at one-second intervals.

The diagram shows the position of the ball at 0 seconds, 1 second, 2 seconds and 3 seconds, as it rolls down the ramp. Show where you would expect the ball to be at each interval between 4 seconds and 10 seconds.

2.The distance–time graph shows the journey of a golf ball from the tee to the hole.

Use the graph to answer the following questions.

a) How many shots did the golfer take? ………………….

b) What was the total distance travelled by the ball? ………………….

c) How far did the golfer’s longest shot go? ………………….

Four sections of the graph are curved rather than straight. Explain what this shows.

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There are different types of speed cameras. Some measure the mean (average) speed of a car over a certain distance, such as a kilometre or a mile. They do this by timing how long it takes for a car to cover the distance and then using the speed formula to calculate the mean speed.Using a worked example, explain how a camera calculates the mean speed

over a set distance.

Plenary: Use the graph to answer the questions:

Additional notes:

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Key Vocab:

• Interpret distance–time graphs to learn about

the journeys represented.

• Relate distance–time graphs to situations &

describe what they show.

How long did he stop for?

What was his speed for the first hour?

How long did it take him to run 40km?



In and On: What are the 3 types of variables?:

• Learning outcomes:

• Describe the motion of an object whose speed is changing.

• Devise questions that can be explored scientifically.

• Present data so that it can be analysed to answer questions.

Watch the teacher demo and answer the following questions:

Explain why the car accelerates down the ramp:

_______________________________________________________________

_______________________________________________________________

Explain why the car decelerates once it reaches the ground:

_______________________________________________________________

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Challenge: Why do the forces in the first part of the journey make it accelerate

and those in the second part make it decelerate?

_______________________________________________________________

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Practical: Investigating motion of a car on a ramp

Hypothesis: The ___________ the ramp, the ____________

the distance travelled by the car.

Variables:

Independent Variable: _____________________________________

Dependent Variable: ______________________________________

Control Variable(s): _______________________________________

_______________________________________________________

Method:

For your first height, place the car at the top of the ramp. Let it go,

and then record the distance it travels from the bottom of the ramp

to where it stops. Repeat this twice more, then increase the height.

Keep doing this until you have reached the maximum height.

Calculate the mean distance travelled by the car for each height

Plot your results as a line graph on the next page

Height of

ramp (m)Distance travelled by the car (m)

Try 1 Try 2 Try 3 Mean

Results table:

0.1

0.2

0.3

0.4

0.5

0.22

0.35

0.45

0.58

0.68

0.25 0.27

0.36 0.34

0.45 0.45

0.52 0.56

0.61 0.63

Describe the pattern shown on the graph.

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Write a conclusion of your results – what did you find?

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Explain your findings – link this to your knowledge of forces

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Why was a line graph the most appropriate graph for this experiment?

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Evaluate the experiment – did anything go wrong? Why? Is your data

reliable? How could you improve the practical?

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Lesson 5: Relative motion

In and On: Which one of the below speeds is the fastest?

30 m/s

1800 m/minute

108,000 m/hour

946,080,000 m/year

Learning outcomes:

• Describe the motion of objects in relation to each other.

• Explain the concept of relative motion.

• Apply the concept of relative motion to various situations.

Define relative speed:

Answer the questions on relative speed using the example below:

A person sets off jogging along a canal path at 12 km/h at the same

time as a boat sets off at 10 km/h.

a) How far will each one travel in half an hour?

_______________________________________________________

b) What is their relative speed?

_______________________________________________________

c) To the jogger, how would the boat appear to be moving as they

travel along the canal?

_______________________________________________________

Time

(minutes)

Distance (km)

CAR A

Distance (km)

CAR B

0 0 0

2 2 0

4 4 4

6 6 8

8 8

Task: On the next

page, plot a graph of

the data in the table.

This will need to be 2

lines drawn on the

same graph. Then

answer the questions

that follow based on

your graph.

Which car set of the latest?

If they were in the same lane when would they crash?

Which car finished their journey first?

Which car had the fastest speed?

What is their relativistic speed?

Challenge Question – Why are head on collisions so dangerous?

Task 1:

The diagrams show two cars travelling along a road in the same direction. The cars are travelling at different but constant speeds. Picture 2 is taken 10 secs after picture 1.

a) How far has each car travelled between picture 1 and picture 2?

_____________________________________________________________

b) Calculate the speed of each car in m/s

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c) What is the relative speed of the two cars?

____________________________________________________________

d) How far apart will the two cars be after a further 5 seconds has passed?

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e) Add a third car to the diagram above, which starts 10 m ahead of car A, but travels at half the speed of car A.

Task 2: Two cars are driving along a road in the same direction. The car in front, driven by Alex, is travelling at a steady speed of 15 m/s. The car following, driven by Georgie, is catching up and is travelling at 20 m/s. Draw a diagram similar to the one in task 1, to show an 800 m stretch of road. The faster car is 100 m from the start. The slower car is 100 m ahead. Mark the position and direction of travel of the two cars.

b) Georgie’s car pulls alongside Alex’s car 20 s after the diagram in part a). What position on the stretch of road will they have reached?

c) Draw a second diagram to show the new position of each car when Georgie is alongside Alex.

Challenge: A third car is driven by Asma and is travelling in the opposite direction to Georgie and Alex. It starts at the far end of the end of the 800 m stretch of road and is travelling at 10 m/s.

a) Add the position of Asma’s car to the two diagrams you drew in task 2.

b) If all cars continue at their same speeds, Could Georgie overtake safely?

c) What advice would you give to Georgie about overtaking?

d) Add to both diagrams a police car that is rushing to an emergency. It is travelling in the same direction as Alex and Georgie at a speed of 40 m/s. In the first diagram it is 100 m behind Georgie.

e) Suggest why police emergency response drivers need to be very highly trained.

Plenary: Which scenario is worse? Explain your answer:

Additional notes:

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Key Vocab:

• Describe the motion of objects in relation to

each other.


• Apply the concept of relative motion to

various situations

a) A car travelling at 10 km/h and colliding with a parked car.

b) A car travelling at 70 km/h and colliding with a car going 60 km/h in the

same direction.

c) A car travelling at 70 km/h and colliding with a car doing 60 km/h in the

opposite direction.


In and On: How many different forces can you name?


• Recognise different examples of forces.

• List the main types of force.

• Represent forces using arrows.

What 3 things can a force do?

A force is: _______________________________________________

• Weight

• Upthrust

• Friction

• Air Resistance

• Lift

• upward force exerted on an object in a fluid

• resistive force due to moving through air

• resistive force due to 2 objects in contact

• force that uses motion to make an object rise up

• downwards force due to gravity

Task: Match the force to what it does

Task: Add arrows to show the forces

acting on a person who is stationary

Task: Add arrows to show the forces acting on

a car which is travelling at a constant speed

Add force arrows to show the correct forces acting on each object.

Chose from the options below:

Weight Friction Upthrust Reaction

Lift Forward force Air resistance

If forces are balanced, an object will be _______________ or travelling

at a __________ speed. Unbalanced forces lead to a change in ______

(acceleration or deacceleration) or in ______________.

Task: Show arrows on each diagram below for the different scenarios

Team A pulls to the left and team B pulls to the right with the same-sized forces.

Team B pulls with a larger force Team A pulls with a larger force

Describe in words what happens in a tug-of-war when:

i) the forces are balanced

________________________________________________________________________

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ii) the forces are unbalanced.

_________________________________________________________________________

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2. A tennis player hits a ball using a racket. Think about the forces acting on the ball at different stages of a tennis match and answer these questions.

a) Explain how the ball can still be moving when it is no longer in contact with the racket.

_________________________________________________________________________

_________________________________________________________________________

b) What forces act on the ball during its flight?

_________________________________________________________________________

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c) When a ball has rolled to a stop, what forces (if any) are acting?

_________________________________________________________________________

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Challenge: Forces are at work when a firework rocket is set off. Describe and

explain the forces involved during the flight of the rocket

Plenary: Add arrows to the two plane. The first is at a constant height

and speed, the second accelerating towards the ground

Additional notes:

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Key Vocab:

Lesson 7: Weight, Mass and gravity

In and On: What is mass? What is weight? Are they the same thing? Explain

Learning outcomes:

• Describe gravity as a non-contact force.

• Explore the concepts of gravitational field and weight.

• Explain how weight is related to mass.

Mass is: _________________________________________________

________________________________________________________

Weight is: _______________________________________________

________________________________________________________

Gravity is: _______________________________________________

________________________________________________________

Weight = ______ x ______ (weight measured in ___)

Mass = ________ / _____ (mass measured in ____)

Gravity = ______ / _____ (gravity measured in ____)

An astronaut has a mass of 80 kg. When will he weigh more? Earth – g = 10N/kg Moon – g = 1.5N/kg

The gravitational field strength on earth is around 10 N/kg. What

is your weight if your mass is 45 kg?

My mass is __________. On earth my weight is _______. (g = 10N/kg)

On Mars, gravity is 4 N/kg.

If I lived on Mars my MASS would be ………………… kg.

If I lived on Mars my WEIGHT would be ………………… N.

Planet My mass Gravity My weight

Mercury kg 4 N/kg N

Venus kg 9 N/kg N

Earth kg 10 N/kg N

Mars kg 4 N/kg N

Jupiter kg 25 N/kg N

Saturn kg 10 N/kg N

Uranus kg 9 N/kg N

Neptune kg 11 N/kg N

Complete the table:

Does your mass change?

Does your weight change?

Where do you weigh the

most? Least?

Decide which of the following statements are true and which are false.

Rewrite the false ones to change them into true statements.

a) The weight of an object is always the same.

b) Weight is a force, so it is measured in newtons.

c) The mass of an object depends on the strength of the gravitational field.

d) Gravitational field strength gets weaker the further you are from the object causing it.

e) The Earth’s gravitational field reaches to the edge of the atmosphere but no further.

_________________________________________________________

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Use your knowledge about matter, gravitational field strength and forces to explain why, for a particular object, mass does not vary but weight does.

_________________________________________________________

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Imagine a mouse and an elephant falling towards the Earth. Calculate the force due to gravity and the acceleration due to gravity for the mouse with a mass of 100 g and for the elephant with a mass of 5000 kg. Assume that air resistance has no effect. Where it helps, draw diagrams to explain your answer.

Plenary: Mini Quiz!! Write true or False

1) Mass is measured in grams and kilograms.

2) Weight is the same as mass.

3) The moon orbits the sun.

4) Gravitational forces change on other planets.

5) Earth orbits the sun every 24 hours.

6) You weigh less on the moon.

7) Your mass changes in space

Additional notes:

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• Explore the concepts of gravitational field

and weight.


Key Vocab:

RevisionThe next 2 pages are left blank for you to use for revision in

preparation for the end of topic test.

Your teacher may ask you to complete a specific revision activity or ask

you to revise independently.

Suggested activities include: Mind maps, practice questions from the

text book, flash cards, memorising key words and concepts.

Glossary: Throughout the topic – use this page to make not of key

words and their meanings. This can be a revision aid.

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Learning outcomes:





a) 1 hour?

b) 2 Hours?

c) 5 Hours?

d) 30 minutes?

Speed is ____________________________________________










e) 1 km in 1 minute


Challenge:




50 x 1 = 50 miles

50 x 2 = 100 miles

50 x 5 = 250 miles

50 x 0.5 = 25 miles

The distance travelled in a certain time

100 ÷ 20 = 5 m/s

48 ÷ 4 = 12 m/s

57 ÷ 3 = 19 m/s

3000 ÷ 100 = 30 m/s

1000 ÷ 60 = 16.7 m/s

350 ÷ 5 = 70 km/h



Learning outcomes:





a) 1 hour?

b) 2 Hours?

c) 5 Hours?

d) 30 minutes?

Speed is ____________________________________________










e) 1 km in 1 minute


Challenge:




50 x 1 = 50 miles

50 x 2 = 100 miles

50 x 5 = 250 miles

50 x 0.5 = 25 miles

The distance travelled in a certain time

100 ÷ 20 = 5 m/s

48 ÷ 4 = 12 m/s

57 ÷ 3 = 19 m/s

3000 ÷ 100 = 30 m/s

1000 ÷ 60 = 16.7 m/s

350 ÷ 5 = 70 km/h

50 x 3 x 60 x60

= 540,000 m

Practical:Aim: calculate the speed of various ways to move

Imagine a normal journey across a town that is 15 km across. The car

sets off at 9.00 am and arrives at 11.00 am. During the journey the

car reaches a highest speed of 50 km/h but has to slow down for

traffic and stop several times at junctions.

a) Work out the overall average speed for the journey.

b) Explain why the average speed is so much lower than the highest

speed.

c) Two cyclists, Victoria and Laura, also set off at 9.00 am and head

for the same destination as the car. Victoria takes the same route

as the car and arrives at 10.30 am. Laura takes the ring road,

which is a distance of 22 km, and arrives at 10.15 am. Work out

the average speeds of the two cyclists.

d) Suggest reasons why Laura arrived first despite taking the longer

route.

Challenge task: Average speedsRead the information & complete the questions.

Speed = distance ÷ time 15 ÷ 2 = 7.5 km/h

The car’s speed is slower than the top speed for some

of the journey and this decreases the average value.

VICTORIA Speed = distance ÷ time 15 ÷ 1.5 = 10 km/h

LAURA Speed = distance ÷ time 22 ÷ 1.25 = 17.6 km/h

Laura didn’t stop at junctions or

Laura is fitter than Victoria

Additional notes:

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Key Vocab:

Speed limits are enforced in the UK.

Write down reasons why these are important.

Why can you go faster on the motorway than in an urban area?

Slower speeds are safer. Drivers have more time to react to incidents.

Collisions at slower speeds cause fewer injuries and fewer deaths.

Motorways are straighter and flatter. Visibility is better. They have

fewer turns with smaller turning angles. Lanes are wider so there is

more room for vehicles to pass each other.

Speed

Distance

Time

Collision

Faster

Slower


In and On: Look at the picture of the graph.

Discuss with a partner what you think this

represents.

Learning outcomes:




A journey can be represented using a distance time graph.

The graph shows a cyclists journey.

1) What units could measure the cyclists speed?

2) How far did they travel in the first 6 seconds?

3) What was the cyclists speed?

4) Sketch another line to show the journey of a

cyclist who is travelling at half the speed.

For each graph below – write a few words to describe the speed of each

Suggestions: Constant speed, stationary, accelerating, decelerating.

Challenge: What about the direction of the movement?

m/s

30 m

Speed = distance ÷ time 30 ÷ 6 = 5 m/s

stationary Constant speed

forward

Constant speed

backwards

Speeding up

(accelerating)

Slowing down

(decelerating)

Constant speed forward

(slower than B)

Task 1: Write a brief description of each journey shown on the graphs

a) ______________________________________________________

_________________________________________________________

b) _______________________________________________________

_________________________________________________________

c) _______________________________________________________

_________________________________________________________

d) _______________________________________________________

_________________________________________________________

Time (min) 0 10 15 20 30 40 50 60 70 80 90

Distance travelled by car (km) 0 10 10 15 20 40 60 65 70 75 80

Distance travelled by train (km) 0 20 30 40 40 60 80 80 80 80 80

Task 2: On the same graph, plot a distance time graph for each journey

From your graph, answer these questions:

Identify the times when:

i) the car was not moving __________________

ii) the train was not moving. __________________

What was the total journey time for:

i) the car ___________________

ii) the train? ___________________

Constant speed forward then stationary (stopped)

Constant speed forward (slow) then constant speed forward

(fast) then stationary (stopped)

Constant speed forward

Speeding up (accelerating) then slowing down (decelerating)

then stopped (stationary)

Between 10 and 15 mins

Between 20 and 30 mins

and after 50 mins

90 mins

50 mins

Challenge questions:

Calculate the fastest speed in km/h achieved by each mode of transport.

Calculate the average speed in km/h over the entire journey for each mode of

transport.

Suggest why one mode of transport has a quicker journey time than the other.

Time (min)

Dis

tan

ce t

rav

ell

ed

(k

m)

20 40 60 80

20

40

60

80

X

XXXX

X

X X

X

X

X

XX

X

X

X

X

X

XX car

train

The car has to travel slowly in town, stopping for traffic lights and

in congestion.

The train has fewer delays and stops at stations.

CAR Speed = distance ÷ time 80 ÷ 90 = 0.89 km/min

TRAIN Speed = distance ÷ time 80 ÷ 50 = 1.6 km/min

#1

#2

CAR #1 Speed = distance ÷ time (60-20)÷(50-30) = 2 km/min TRAIN #2 Speed = distance ÷ time (80-40)÷(50-30) = 2 km/min

Plenary: Complete the sentences:

A horizontal line on a distance-time graph shows

________________________.

The steeper the line on the graph, _______________________.

A curved line shows ____________________________.

Options: Faster the speed / Object is stationary / acceleration or deceleration

Additional notes:

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________________________________________

________________________________________

________________________________________

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Key Vocab:




Object is stationary (stopped)

the faster the speed

Acceleration or deceleration (changing speed)

Acceleration

Deceleration

Accelerating

Decelerating

stationary

Lesson 3: Exploring journeys on distance-time graphs

In and On: Solve the anagrams:

Deeps: _________ Ratgiend: _________ Veeraag: ___________

Learning outcomes:

• Interpret distance–time graphs to learn about the journeys represented.

• Relate distance–time graphs to situations & describe what they show.

Task 1: Work out the missing values, use the triangle to help

Distance = 130 milesSpeed = ? mphTime = 2 hours

Distance = ? KmSpeed = 13 km/hTime = 3 hours

3. Distance = 48 mSpeed = 4 m/sTime = ? Seconds

Distance = 60 milesSpeed = ? mphTime = 30 minutes

Distance = 20 kmSpeed = ? km/hTime = 15 minutes

Task 2: Can you match the pictures with their respective graphs?

Challenge: Explain your choices:

speed gradient average

130 ÷ 2 = 65 mph 13 x 3 = 39 km 48 ÷ 4 = 12 s

60 ÷ 0.5

= 120 mph

20 ÷ 0.25

= 80 km/h

A

E

B

D

C

Acceleration

On a distance–time graph, a _____

slope shows that an object is travelling

_______ than an object with a shallow

slope. If the object rapidly _________,

the slope of the line will change

rapidly. However, if the change in

speed is more gradual, the _______

will change more gradually.

Which object has the fastest starting speed? _____

Which object has the fastest final speed? _____

Task 3: Write a short story describing each graph:

Task 4: Complete the following questions: The distance–time graph shows the journey of a tennis ball rolling down a ramp and across the floor.

a) Label the curve to show:

1. where the ball is travelling fastest

2. where the ball is accelerating

3. where the ball is slowing down

4. where the ball is stationary.

b) Explain why the ball speeds up for part of its journey and slows down for part of its journey.

steep

faster

accelerates

gradient

B

C

A person drives a

friend’s house at

constant speed,

stops for an hour

and drives home at

constant speed.

A bus leaves school

at drives at constant

speed to a museum.

Pupils visit for 1 hour.

The return journey

takes 30min.

A cyclist rides home

fast for 15 mins.

She stops for 30min

for lunch. She rides

slowly back for the

remaining 12km.

2

1

3

4

Gravity makes the ball speed

up as it goes down the ramp

Friction makes the ball slows down as it moves over the floor

Imagine it took 10 seconds from the moment the ball was released to when it finally came to rest. If the motion was videoed and the recording was stopped after each second, we would see the position of the ball at one-second intervals.

The diagram shows the position of the ball at 0 seconds, 1 second, 2 seconds and 3 seconds, as it rolls down the ramp. Show where you would expect the ball to be at each interval between 4 seconds and 10 seconds.

2.The distance–time graph shows the journey of a golf ball from the tee to the hole.

Use the graph to answer the following questions.

a) How many shots did the golfer take? ………………….

b) What was the total distance travelled by the ball? ………………….

c) How far did the golfer’s longest shot go? ………………….

Four sections of the graph are curved rather than straight. Explain what this shows.

________________________________________________________

________________________________________________________

________________________________________________________

________________________________________________________

There are different types of speed cameras. Some measure the mean (average) speed of a car over a certain distance, such as a kilometre or a mile. They do this by timing how long it takes for a car to cover the distance and then using the speed formula to calculate the mean speed.Using a worked example, explain how a camera calculates the mean speed

over a set distance.

0 1 2 34 5 6 7 8 9 10

4

460 m

210 m

Shot 1

Shot 2

Shot 3

Shot 4

The speed of the ball is changing. The collision with the golf club

makes the ball speed up. Air resistance slows the ball in flight.

Friction slows the ball as is rolls on the grass.

1. Measure the start time as the car enters the measured mile.

2. Measure the end time as the car finishes the measured mile.

3. Calculate the speed using :

speed = distance ÷ time

= 1 ÷ (end time – start time)

Plenary: Use the graph to answer the questions:

Additional notes:

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________________________________________

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Key Vocab:

• Interpret distance–time graphs to learn about

the journeys represented.

• Relate distance–time graphs to situations &

describe what they show.

How long did he stop for?

What was his speed for the first hour?

How long did it take him to run 40km?

8 km

Speed = distance ÷ time 10÷1 = 10 km/h

15 min ( ¼ of an hour)

2 hours 45 min (2 and ¾ hours)

Speed

Distance

Friction

Accelerate

Air resistance



In and On: What are the 3 types of variables?:


• Describe the motion of an object whose speed is changing.

• Devise questions that can be explored scientifically.

• Present data so that it can be analysed to answer questions.

Watch the teacher demo and answer the following questions:

Explain why the car accelerates down the ramp:

_______________________________________________________________

_______________________________________________________________

Explain why the car decelerates once it reaches the ground:

_______________________________________________________________

_______________________________________________________________

Challenge: Why do the forces in the first part of the journey make it accelerate

and those in the second part make it decelerate?

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

1. Independent variable

2. Dependent variable

3. Control variable

Gravity pulls the car down the slope and makes the car speed up.

Friction between the car and the ground makes the car slow

down.

On the ramp, gravity pulls the car down the slope and

affects the motion of the car.

On the ground, only air resistance and friction with the ground

affect the motion of the car.

Practical: Investigating motion of a car on a ramp

Hypothesis: The ___________ the ramp, the ____________

the distance travelled by the car.

Variables:

Independent Variable: _____________________________________

Dependent Variable: ______________________________________

Control Variable(s): _______________________________________

_______________________________________________________

Method:

For your first height, place the car at the top of the ramp. Let it go,

and then record the distance it travels from the bottom of the ramp

to where it stops. Repeat this twice more, then increase the height.

Keep doing this until you have reached the maximum height.

Calculate the mean distance travelled by the car for each height

Plot your results as a line graph on the next page

Height of

ramp (m)Distance travelled by the car (m)

Try 1 Try 2 Try 3 Mean

Results table:

higher bigger

Height of the ramp

Distance moved after the end of the ramp

Same toy car ,

Same ramp length and same ramp material

0.1

0.2

0.3

0.4

0.5

0.22

0.35

0.45

0.58

0.68

0.25 0.27

0.36 0.34

0.45 0.45

0.52 0.56

0.61 0.63

0.24

0.35

0.45

0.55

0.64

0.1 0.2 0.3 0.4 0.5

Height of ramp (m)

Dis

tan

ce t

rav

ell

ed

by

th

e c

ar

(m

)

0.1

0.2

0.3

0.4

0.7

0.6

0.5

X

X

X

X

X

Describe the pattern shown on the graph.

Write a conclusion of your results – what did you find?

Explain your findings – link this to your knowledge of forces

Why was a line graph the most appropriate graph for this experiment?

Evaluate the experiment – did anything go wrong? Why? Is your data

reliable? How could you improve the practical?

As the height of the ramp increases, the distance travelled by the

car increases.

The graph line is a straight line for ramp heights bigger than 0.2m.

More data is needed for heights less than 0.1m. Results for 0.1m

and 0.5m have a range of 0.05m so more trys would give a better

mean.

The data is continuous. The height of the ramp and the distance

travelled can have any value.

A steeper ramp gives more force downwards along the ramp. The

friction force with the ramp gets less so the car leaves the ramp at

a faster speed and with more energy.

From 0.1m to 0.5m, increasing the height of the ramp increased the

distance travelled by the car proportionally (straight line)

Lesson 5: Relative motion

In and On: Which one of the below speeds is the fastest?

30 m/s

1800 m/minute

108,000 m/hour

946,080,000 m/year

Learning outcomes:

• Describe the motion of objects in relation to each other.


• Apply the concept of relative motion to various situations.

Define relative speed:

Answer the questions on relative speed using the example below:

A person sets off jogging along a canal path at 12 km/h at the same

time as a boat sets off at 10 km/h.

a) How far will each one travel in half an hour?

_______________________________________________________

b) What is their relative speed?

_______________________________________________________

c) To the jogger, how would the boat appear to be moving as they

travel along the canal?

_______________________________________________________

Time

(minutes)

Distance (km)

CAR A

Distance (km)

CAR B

0 0 0

2 2 0

4 4 4

6 6 8

8 8

Task: On the next

page, plot a graph of

the data in the table.

This will need to be 2

lines drawn on the

same graph. Then

answer the questions

that follow based on

your graph.

They are all the same actual speed.

Each value matches a different unit.

Relative speed is how much faster one object is travelling

compared to another object.

Distance = speed x time JOGGER 12 x 0.5= 6km, BOAT 10X0.5= 5km

Jogger is 2km/h faster than the boat

backwards

Which car set off the latest?

If they were in the same lane when would they crash?

Which car finished their journey first?

Which car had the fastest speed?

What is the speed of car B relative to car A ?

Challenge Question – Why are head on collisions so dangerous?

Dis

tan

ce t

rav

ell

ed

(k

m)

5

3

1

6

4

2

7

8

654321 87

Time (min)

X

X

X

X

X

Car A

X

X

X

Car B

Car B

4 mins or 4 km

Car B

Car B

Car A speed = 8 ÷ 8 = 1 km/h

Car B speed = 8 ÷ 6 = 1.33 km/hCar B speed relative to car A 1.33 – 1 = 0.33 km/h

The relative speed of the collision is

both car speeds added together

Task 1:

The diagrams show two cars travelling along a road in the same direction. The cars are travelling at different but constant speeds. Picture 2 is taken 10 secs after picture 1.

a) How far has each car travelled between picture 1 and picture 2?

_____________________________________________________________

b) Calculate the speed of each car in m/s

_____________________________________________________________

c) What is the relative speed of the two cars?

____________________________________________________________

d) How far apart will the two cars be after a further 5 seconds has passed?

_____________________________________________________________

e) Add a third car to the diagram above, which starts 10 m ahead of car A, but travels at half the speed of car A.

Task 2: Two cars are driving along a road in the same direction. The car in front, driven by Alex, is travelling at a steady speed of 15 m/s. The car following, driven by Georgie, is catching up and is travelling at 20 m/s. Draw a diagram similar to the one in task 1, to show an 800 m stretch of road. The faster car is 100 m from the start. The slower car is 100 m ahead. Mark the position and direction of travel of the two cars.

b) Georgie’s car pulls alongside Alex’s car 20 s after the diagram in part a). What position on the stretch of road will they have reached?

c) Draw a second diagram to show the new position of each car when Georgie is alongside Alex.

Challenge:

e) Suggest why police emergency response drivers need to be very highly trained.

Car A

70

40

120

Car B

Car A 70 - 0 = 70 m Car B 120 - 40 = 80 m

Car A speed = 70 ÷ 10 = 7 m/s Car B speed = 80 ÷ 10 = 8 m/s

Relative speed = Speed car B – speed car A 8 – 7 = 1 m/s

Current distance apart (50m) + relative extra (1x5) = 55m

C

C10 + 35 = 45

a) Asma is at the far right-hand end in the first diagram, and 200 m from the right-hand end in the second diagram.

b) Not very likely; there is a risk of a head-on collision in just over 3 s.

c) Overtake as fast as possible; wait for a dual carriageway; be patient; choose not to overtake, because it is unsafe.

d) Police car is at the far left-hand end in first diagram, and at the far right-hand end in the second.

e) They need to be able to judge speed of a car and judge risks well. They must not put the public in danger.

200 400 600 800

200 400 600 800

G A

AG 500m from the left side

Plenary: Which scenario is worse? Explain your answer:

Additional notes:

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________


Key Vocab:

• Describe the motion of objects in relation to

each other.


• Apply the concept of relative motion to

various situations

a) A car travelling at 10 km/h and colliding with a parked car.

b) A car travelling at 70 km/h and colliding with a car going 60 km/h in the

same direction.

c) A car travelling at 70 km/h and colliding with a car doing 60 km/h in the

opposite direction.

Relative speed = moving car speed – parked car speed

= 10 – 0 = 10 km/h

Relative speed = car 1 speed (70 km/h) – car 2 speed (60 km/h)

= 10 km/h

Relative speed = car 1 speed (70 km/h) – car 2 speed (-60 km/h)

= 70 + 60

= 130 km/h

Relative

Speed

km/h


In and On: How many different forces can you name?





What 3 things can a force do?

A force is: _______________________________________________

• Weight

• Upthrust

• Friction

• Air Resistance

• Lift

• upward force exerted on an object in a fluid

• resistive force due to moving through air

• resistive force due to 2 objects in contact

• force that uses motion to make an object rise up

• downwards force due to gravity

Task: Match the force to what it does

Task: Add arrows to show the forces

acting on a person who is stationary

Task: Add arrows to show the forces acting on

a car which is travelling at a constant speed

1. Change object’s speed

2. Change object’s shape

3. Change moving object’s direction

weight

Reaction from ground Reaction from ground

weight

thrustAir

resistance

Add force arrows to show the correct forces acting on each object.

Chose from the options below:

Weight Friction Upthrust Reaction

Lift Forward force Air resistance

weight

weightweight

weightweight

weight

weightweight

weight

upthrust

upthrustReaction

Reaction

Force up from spring

Force up from hand

Force up from string

reaction

If forces are balanced, an object will be _______________ or travelling

at a __________ speed. Unbalanced forces lead to a change in ______

(acceleration or deacceleration) or in ______________.

Task: Show arrows on each diagram below for the different scenarios

Team A pulls to the left and team B pulls to the right with the same-sized forces.

Team B pulls with a larger force Team A pulls with a larger force

Describe in words what happens in a tug-of-war when:

i) the forces are balanced

________________________________________________________________________

_________________________________________________________________________

ii) the forces are unbalanced.

_________________________________________________________________________

_________________________________________________________________________

2. A tennis player hits a ball using a racket. Think about the forces acting on the ball at different stages of a tennis match and answer these questions.

a) Explain how the ball can still be moving when it is no longer in contact with the racket.

_________________________________________________________________________

_________________________________________________________________________

b) What forces act on the ball during its flight?

_________________________________________________________________________

_________________________________________________________________________

c) When a ball has rolled to a stop, what forces (if any) are acting?

_________________________________________________________________________

_________________________________________________________________________

Challenge: Forces are at work when a firework rocket is set off. Describe and

explain the forces involved during the flight of the rocket

stationary

constant speed

direction

stationary

Move right Move left

Equal forces act in opposite directions. The rope remains

stationary.

Unequal forces act in opposite directions. The rope moves in the

direction of the biggest force.

The ball moves at a constant speed in a straight line until another

force acts on it and changes its motion.

Air resistance acts in the opposite direction to the direction of

motion. Weight acts downwards.

Weight acts downwards. Reaction force upwards from the

ground.

1. The rocket moves up because the thrust upwards is

bigger than the weight downwards.

2. The rocket slows down because the air resistance force

is in the opposite direction to the rocket’s motion.

Plenary: Add arrows to the two plane. The first is at a constant height

and speed, the second accelerating towards the ground

Additional notes:

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

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Key Vocab:

weight

lift

Engine

thrust

Air

resistance

lift

weight

Weight

Upthrust

Lift

Friction

Air resistance

thrust

Lesson 7: Weight, Mass and gravity

In and On: What is mass? What is weight? Are they the same thing? Explain

Learning outcomes:


• Explore the concepts of gravitational field and weight.


Mass is: _________________________________________________

________________________________________________________

Weight is: _______________________________________________

________________________________________________________

Gravity is: _______________________________________________

________________________________________________________

Weight = ______ x ______ (weight measured in ___)

Mass = ________ / _____ (mass measured in ____)

Gravity = ______ / _____ (gravity measured in ______)

An astronaut has a mass of 80 kg. When will he weigh more? Earth – g = 10N/kg Moon – g = 1.5N/kg

The gravitational field strength on earth is around 10 N/kg. What

is your weight if your mass is 45 kg?

A measure of how much matter or particles an

object has.

A measure of how strongly gravity pulls on an

object’s matter.

A field that causes an attraction force between object

because all objects have mass

mass gravity

mass

gravityweight

weight

N

kg

N/kg

Weight = mass x gravity 45 x 10 = 450 N

Weight = 80 x 10

= 800 N

Weight = 80 x 1.5

= 120 N

My mass is __________. On earth my weight is _______. (g = 10N/kg)

On Mars, gravity is 4 N/kg.

If I lived on Mars my MASS would be ………………… kg.

If I lived on Mars my WEIGHT would be …………………………… N.

Planet My mass Gravity My weight

Mercury kg 4 N/kg N

Venus kg 9 N/kg N

Earth kg 10 N/kg N

Mars kg 4 N/kg N

Jupiter kg 25 N/kg N

Saturn kg 10 N/kg N

Uranus kg 9 N/kg N

Neptune kg 11 N/kg N

Complete the table:

Does your mass change?

Does your weight change?

Where do you weigh the

most? Least?

Decide which of the following statements are true and which are false.

Rewrite the false ones to change them into true statements.

a) The weight of an object is always the same.

b) Weight is a force, so it is measured in newtons.

c) The mass of an object depends on the strength of the gravitational field.

d) Gravitational field strength gets weaker the further you are from the object causing it.

e) The Earth’s gravitational field reaches to the edge of the atmosphere but no further.

_________________________________________________________

_________________________________________________________

Use your knowledge about matter, gravitational field strength and forces to explain why, for a particular object, mass does not vary but weight does.

_________________________________________________________

_________________________________________________________

Imagine a mouse and an elephant falling towards the Earth. Calculate the force due to gravity and the acceleration due to gravity for the mouse with a mass of 100 g and for the elephant with a mass of 5000 kg. Assume that air resistance has no effect. Where it helps, draw diagrams to explain your answer.

45 kg 450 N

45

45 x 4 = 180 N

45

4545

45

45

45

4545

180

405

450

180

450

405

405

1125

no

yes

Most = Jupiter

Least = Mercury or Mars

falseThe mass of an object is always the same.

true

falseThe weight of an object depends on the strength of the gravitational field.

true

Gravity goes to the edge of the Universe. The Earth’s gravity pulls

on the Moon and makes the Moon orbit around the Earth.

false

Mass depends on the number of particles in an object. The number

of particles does not change when the object is moved. Weight

depends on gravity and gravity is not the same everywhere.

MOUSE mass = 100 ÷ 1000 = 0.1 kg weight = 0.1 x 10 = 1 N

ELEPHANT mass = 5000 kg weight = 5000 x 10 = 50,000 N

Plenary: Mini Quiz!! Write true or False

1) Mass is measured in grams and kilograms.

2) Weight is the same as mass.

3) The moon orbits the sun.

4) Gravitational forces change on other planets.

5) Earth orbits the sun every 24 hours.

6) You weigh less on the moon.

7) Your mass changes in space

Additional notes:

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________

________________________________________



• Explore the concepts of gravitational field

and weight.


Key Vocab:

true

true

true

false

false

false

false

Mass

Weight

Newton

Kilogram

Gravitational

Particles

N

kg

N/kg

KS3 Science Forces 1 - Rastrick High School...2020/12/07 · KS3 Science Forces 1 Home Learning...

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Transcript of KS3 Science Forces 1 - Rastrick High School...2020/12/07 · KS3 Science Forces 1 Home Learning...