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Question 1

Speed is — and has units—.

Answer 1

the distance divided by time; m/s or km/h

Question 2

In UK and USA, speeds are usually measured in–.

Answer 2

mph (=miles per hour)

Question 3

3 kinds of speed

Answer 3

steady s (speed X change)
average s (total distance/ total time)
instantaneous s (speed at particular moment)

Question 4

precision is shown by the number of –. (-=)

Answer 4

Significant figures ( the numbers of digits in a number )

Question 5

precision

Answer 5

The number of decimal places given for measurement

Question 6

accuracy

Answer 6

How close a measurement is to a true value

Question 7

When – was first introduced, the measure times for the 100 m got -! When the stopwatch was used there was —. This - is called –. (=–)

Answer 7

automatic timing; longer;a short delay between the judge hearing the gun and starting the stopwatch; delay; reaction time; the time that it takes the brain to process information (0.2 sec)

Question 8

how does automatic timing works (3)

Answer 8

The starter’s gun triggers the start of the timer
the athlete breaks a light beam when their body crosses the line
the light sensor automatically stops the clock.

Question 9

distance-time graph (2)

Answer 9

measure the distance a moving object has travelled from its starting point each second
plot a distance-time graph

Question 10

When the speed does not change, the graph–

Answer 10

is a straight line.

Question 11

The slope, or -, of a distance-time graph tells you –.
When the slope is flat, the speed is —, and the object–.

Answer 11

gradient; the speed
zero, is not moving

Question 12

A more realistic graph would have - lines as our speed change —.

Answer 12

curved; gradually (we don’t suddenly change speed)

Question 13

A distance-time graph for a falling ball will – because –. It is a –. This shows that the speed is -.

Answer 13

not be a straight line; the speed is not constant; a curve and the slope is increasing; increasing (acclerating)

Question 14

acceleration= (units:)

Answer 14

final speed (v) -initial speed(u)/ time m/s^2

Question 15

If the final speed is —, it means that the object is slowing down or decelerating. The acceleration is -.

Answer 15

lower than the starting speed; negative.

Question 16

• The gradient of a line on a distance-time graph tells you about –.
• The gradient of a line on a speed-time graph tells you about –.

Answer 16

the speed of an object; its acceleration

Question 17

• A straight, sloping line on a speed-time graph shows –.
• A horizontal line on a speed-time graph shows –.

Answer 17

constant acceleration; constant speed

Question 18

When the line of a speed-time graph gets less and less steep, his—-. This does not mean –. It means that –. The force of —. Eventually he travels at a steady, –. The line is horizontal because his speed is –.

Answer 18

changes less quickly; that he is slowing down; it takes longer for his speed to increase; air resistance increases until eventually it balances the forward force; terminal velocity; no longer changing

Question 19

If one of the variables in your table is a discrete variable, then you will need to –.

Answer 19

plot a bar chart or pie chart

Question 20

The speed of a racing car is a –.

Answer 20

continuous variable because it varies all the time

Question 21

On a distance-time graph for a car:
— 3

Answer 21

• when the line is horizontal the car is stationary
• a straight sloping line means that the car is moving at a steady speed
• when the line curves up the car is accelerating.

Question 22

On a speed-time graph for a car:
– 2

Answer 22

• when the line is horizontal, the car is moving at a steady speed
• a straight sloping line means that the car is accelerating at a steady rate.

Question 23

When both variables are continuous, - are used.

Answer 23

line graphs

Question 24

When an object is balanced it behaves as if – When the diver floats, her —.

Answer 24

there is no force on it.; weight is balanced by the upthrust of the water

Question 25

If the forces on an object are balanced, its ---: 2

Answer 25

motion will not change * If it is not moving it will stay still. (stationary) * If it is moving it will keep moving at a steady speed.

Question 26

If the forces --, they are unbalanced. If the forces are unbalanced then the --: 2

Answer 26

on an object are not equal and opposite motion of the object will change * If it is not moving it will start moving. * Ifit is moving it will speed up (accelerate), slow down (decelerate), or change direction.

Question 27

If you know the---, you can work out the --, or net force.

Answer 27

size of each force acting on an object; resultant force

Question 28

* If the resultant force is zero the --. * If the resultant force is not zero the --.

Answer 28

forces are balanced forces are unbalanced

Question 29

An object can ---. It will move at a steady speed.

Answer 29

move without a resultant force

Question 30

Thought experiement

Answer 30

the process of thinking through what might happen in an experiment without actually doing it

Question 31

All surfaces, even surfaces that feel very smooth, are- .

Answer 31

uneven

Question 32

* If you push a book on a table and it does not move, the forces are -. * The uneven surfaces produce the ---. * When your force is bigger than friction, the forces are -. * Then the book will --.

Answer 32

balanced; force of friction that you have to overcome; unbalanced; accelerate

Question 33

When the force applied is ---, the object will move.

Answer 33

larger than the maximum fraction

Question 34

3 ways to reduce friction

Answer 34

1. Skiers and snowboarders wax their skis. 2. You put oil in a car to reduce friction between engine parts that move. This is called lubrication. Cyclists lubricate the chains of their bicycles. 3. Ball-bearings inside the wheels of a skateboard roll over each other as wheel turns. (slow down surface wear)

Question 35

How does lubrication work?

Answer 35

A layer of oil between two surfaces makes it easier for the surfaces to slide over each other. It reduces the force of friction. There will be less collision of the bumps; the surfaces will slide over each other more easily.

Question 36

3 usefulness of friction

Answer 36

1. Walk:friction acts between your feet and the ground, making it possible for you to move 2. Vehicles:need the force of friction between the tyres and the road to make them move. 3. Bicycles and cars:friction acts between brakes and wheels to stop (brake pads or brake blocks and the wheels)

Question 37

In icy conditions ---. Wheels skid because ---.

Answer 37

friction is reduced; there is not enough friction for them to grip the road

Question 38

You can use -- to measure the --- between two surfaces.

Answer 38

a newtonmeter; force of friction

Question 39

Friction is useful for -----.

Answer 39

grip, to start moving, or for braking

Question 40

A moving object still needs --- in order to keep it moving at a steady speed.

Answer 40

a force to balance the forces slowing it down

Question 41

Aristotle's ideas about motion

Answer 41

objects move only when they are pushed, and slow down when you remove the force. (no friction)

Question 42

A thought experiment is useful to ----.

Answer 42

what might happen in a situation where it is not possible to carry out the experiment

Question 43

In most situations, the force is needed to ---. Without --, no force is needed to ---.

Answer 43

cancel out friction or air resistance; keep something moving

Question 44

Newton's first law of motion states that, ---

Answer 44

unless an external force is applied, stationary objects will remain stationary, and moving objects will continue to move in a straight line at a steady speed.