9K Word Sheets
9Ka – The need for speed
Word / Pronunciation / Meaningmean speed / The total distance something travels divided by the total time taken allows you to calculate the thing’s mean or average speed.
speed / How fast something is moving. Often measured in metres per second (m/s), miles per hour (mph) or kilometres per hour (km/h).
9Kb – Faster and faster
Word / Pronunciation / Meaningaccelerate / ack-sell-er-ate / Change speed.
air resistance / A force that tries to slow down things that are moving through the air. It is a type of friction.
balanced forces / When two forces are the same strength, but working in opposite directions.
friction / A force that tries to slow things down when two things rub against each other.
unbalanced forces / When two forces working in opposite directions are not the same strength.
9Kc – Drag act
Word / Pronunciation / Meaningdrag / Another name for air resistance or water resistance.
streamlined / Giving something a smooth shape to reduce the air resistance or water resistance.
water resistance / A force that tries to slow down things that are moving through water. It is a type of friction.
9Kd – Hitting the limit
Word / Pronunciation / Meaningdistance–time graph / A graph that shows how far something has moved in a certain time.
terminal velocity / The maximum speed of an object. Usually only applies to falling objects when the downward force is balanced by drag.
QUESTION 1
(a) Megan’s dog is pulling on his lead.
Which arrow, A, B, C or D, shows the direction of this force?
Give the letter.
......
1 mark
(b) Megan has to pull to keep the dog still.
Which arrow shows the direction of this force? Give the letter.
......
1 mark
(c) Suddenly the dog’s collar breaks.
(i) When the collar breaks, the lead moves.
Draw an arrow on the diagram to show which way the lead starts to move.
1 mark
(ii) Why does the lead move when the collar breaks?
......
......
1 mark
Maximum 4 marks
QUESTION 2
Five people take it in turns to sit on a see-saw. The table gives the weight of each person.
person / weight, in NJack / 510
Ellie / 540
Rosie / 490
Maggy / 540
Andy / 560
(a) Andy sits at one end, but there is nobody on the other end.
Andy sits on the see-saw.
In which direction does his end of the see-saw move?
......
1 mark
(b) Which two people in the table above could make the see-saw balance?
………………………..……...…...... and…………………...... ………….
1 mark
Use information in the table to help you answer parts (c) and (d).
(c) Rosie sits on end A, and Jack sits on end B.
They lift their feet.
What happens to each end of the see-saw?
Write up or down in the boxes under Rosie and Jack.
1 mark
(d) Ellie sits on end A, and another of the group sits on end B.
Ellie's end stays down.
Who could be on end B?
......
1 mark
Maximum 4 marks
QUESTION 3
Joe saw two types of swing in the park.
He noticed that the time for one complete swing, forward and back, was different for the two types of swing.
He did not know whether the length of the chains or the mass of the person affected the time for one complete swing.
He made model swings and measured how long it took for 10 complete swings in 4 investigations.
Here are his results.
investigationA / B / C / D
length of string, in cm / 25 / 25 / 50 / 75
mass of plasticine, in g / 100 / 50 / 100 / 100
time for 10 complete swings, in s / 10.0 / 10.0 / 14.2 / 17.4
Here is Joe's conclusion:
(a) Which two of his investigations, A, B, C or D, provided evidence to support his conclusion?
………………….. and …………………….
1 mark
(b) Look at the results table.
(i) Describe how the length of the string affects the time for 10 complete swings.
......
......
1 mark
(ii) Which three of his investigations are best evidence for this?
………………….. and …………………….and …………………
1 mark
(c) Use his previous table of results to predict the times for 10 complete swings in two further investigations, E and F.
Write your answers in the table below.
E / F
length of string, in cm / 25 / 100
mass of plasticine, in g / 25 / 100
time for 10 complete swings, in s / ...... / ......
1 mark
Maximum 4 marks
QUESTION 4
(a) A railway engine is being used to try to pull a wagon along a level track. The wagon’s brakes are on, and the wagon does not move.
(i) Draw one arrow on the diagram to show the direction of the force which prevents the wagon from moving.
1 mark
(ii) Is the force which prevents the wagon from moving greater than, equal to or less than the pull of the engine?
......
1 mark
(b) (i) When the wagon’s brakes are off, the engine pulls the wagon forwards. A frictional force also acts on the wagon. In what direction does the frictional force act?
1 mark
(ii) The pull of the engine is 5000 N. When the wagon’s speed is increasing, how large is the frictional force?
Tick the correct box.
zero
between 0 and 5000 N
5000 N
more than 5000 N
1 mark
(c) After a while, the wagon travels at a steady speed. The engine is still pulling with a force of 5000 N.
How large is the frictional force now?
Tick the correct box.
zero
between 0 and 5000 N
5000 N
more than 5000 N
1 mark
Maximum 5 marks
QUESTION 5
When a car is being driven along, two horizontal forces affect its motion.
One is air resistance and the other is the forward force.
(a) (i) Explain how molecules in the air cause air resistance.
......
......
1 mark
(ii) Explain why air resistance is larger when the car is travelling faster.
......
......
1 mark
(b) (i) Compare the sizes of the forward force and the air resistance when the car is speeding up.
The forward force is
......
1 mark
(ii) Compare the sizes of the two forces while the car is moving at a steady 30 miles per hour.
The forward force is
......
1 mark
(c) The forward force has to be larger when the car is travelling at a steady 60mph than when it is travelling at a steady 30 mph. Why is this?
......
......
1 mark
(d) The forward force is the result of the tyres not being able to spin on the road surface.
What is the name of the force that stops the tyres spinning?
......
1 mark
Maximum 6 marks
QUESTION 6
Anil sits on a mat at the top of a helter-skelter and then slides down a chute around the outside.
(a) (i) Name two of the forces acting on Anil as he slides from point A to point B.
1......
2......
2 marks
(ii) As Anil slides from point A to point B, the forces acting on him are balanced.
Describe Anil's speed when the forces acting on him are balanced.
......
1 mark
(b) Anil goes back for a second go. This time he sits on a smooth cushion instead of a mat.
He goes much faster on the cushion. Give the reason for this.
......
1 mark
(c) On his third go Anil lies back on the cushion with his arms by his side.
What happens to his speed? Give the reason for your answer.
......
......
......
2 marks
Maximum 6 marks
QUESTION 7
In a storm, a small ship was blown onto a beach. Now it is calm and there is no wind. A tugboat is trying to pull the ship off the beach.
(a) The tugboat pulls the ship with a force of 25 000 N.
The ship does not move because of the force of friction acting on it.
(i) Tick one box to show the size of the frictional force acting on the ship.
zero
more than zero but less than 25 000 N
25 000 N
more than 25 000 N
1 mark
(ii) Add an arrow to the drawing to show the direction of the frictional force acting on the ship.
1 mark
(b) When the tide is higher, the tugboat again pulls the ship with a steady force of 25 000 N. The ship begins to move.
Once the ship is off the beach, the tugboat continues to pull the ship with a force of 25 000 N.
A frictional force due to the water acts on the ship.
(i) At first, the speed of the ship increases.
Tick one box to describe the frictional force acting on the ship while its speed is increasing.
zero
more than zero but less than 25 000 N
25 000 N
more than 25 000 N
1 mark
(ii) After a short while, the ship reaches a steady speed. The tugboat continues to pull with a force of 25 000 N.
Tick one box to describe the frictional force acting on the ship while it is going at a steady speed.
zero
more than zero but less than 25 000 N
25 000 N
more than 25 000 N
1 mark
(iii) The ship is towed to the north. What is the direction of the frictional force acting on the ship?
......
1 mark
Maximum 5 marks
QUESTION 8
(a) The ‘two second rule’ is a rule for car drivers. The rule is as follows:
‘Leave enough space between you and the vehicle in front so that you can pull upsafely if it suddenly slows down or stops. . . A two second time gap may be sufficient. . . Use stationary objects (eg lamp-posts) to help you keep a two secondgap.’
(The Highway Code, 1993)
(i) The traffic is moving at 20 m/s, and a driver is keeping to the ‘two second rule’.
What is the distance between the driver and the car in front?
......
1 mark
(ii) The traffic increases its speed to 25 m/s, but the driver stays the same distance from the car in front.
She sees the car in front pass a lamp post.
How long will it take her to reach the same lamp post?
......
...... s
1 mark
(b) The driver decides to check her speedometer while driving along a motorway.
She measures how long it takes her to travel 6 km. It takes her exactly 4 minutes.
What was her speed in km/h? Show your working.
......
......
...... km/h
2 marks
Maximum 4 marks
QUESTION 9
Speed cameras are used to detect motorists who break the speed limit. A number of lines 2 m apart are painted on the road. As a speeding car crosses the painted lines, the camera takes two photographs, 0.5 s apart.
(a) (i) How far did the car move between the two photographs?
Give the correct unit.
......
......
1 mark
(ii) How fast is the car in the photographs moving?
......
...... m/s
1 mark
(b) It takes 0.0002 s to take each photograph.
How far does the car move while the speed camera is taking one photograph?
......
...... m
1 mark
(c) The speed camera gives out bright flashes to provide enough light for the photographs.
How does the light from the flash get back to the camera to produce the photographs?
......
......
1 mark
Maximum 4 marks
QUESTION 10
A video recorder is loaded with a tape which plays for 180 minutes.
The length of the tape is 260 m.
(a) (i) Calculate the speed of the tape, in metres per minute.
……………………………………….………………………………
……………………………………….………………………m/min
1 mark
(ii) What is the speed of the tape in metres per second?
……………………………………….…………………………m/s
1 mark
(b) To rewind the tape quickly, a different motor is used, which rewinds the tape at amaximum speed of 1.08 m/s.
(i) At this speed, how long would it take to rewind the tape completely?
Give the units.
……………………………………….………………………………
……………………………………….………………………………
1 mark
(ii) In fact, it takes slightly longer than this to rewind the tape.
Explain why.
……………………………………….………………………………
1 mark
Maximum 4 marks
QUESTION 11
A remote-controlled car was timed over a period of 10 seconds.
A graph of distance against time is shown below.
(a) Describe the motion of the car between:
(i) 2 seconds and 6 seconds;
......
1 mark
(ii) 9 seconds and 10 seconds.
......
1 mark
(b) Calculate the average speed of the car between 0 and 10 seconds.
Give the unit.
......
......
2 marks
(c) The diagram below shows two of the forces acting on the car when it is moving.
(i) When the motor was switched off, the car slowed down and then stopped.
While the car was slowing down, which of the following was true? Tick the correct box.
Friction was zero and the forwardforce was greater than zero. /
The forward force was zero and
friction was greater than zero. /
Friction was zero and the forward
force was zero. /
The forward force and friction were
both greater than zero. /
1 mark