Motion

Question 1

What is a scalar quantity?

Answer 1

● A quantity that only has a magnitude
but no direction

Question 2

What is a vector quantity?

Answer 2

A quantity that has both a magnitude and a direction.

Question 3

How can a vector quantity be represented?

Answer 3

Using vector arrows.

Question 4

How do vector arrows represent vectors?

Answer 4

● The length of the arrow represents the
magnitude
● The arrow points in the associated
direction

Question 5

Give examples of vector quantities.

Answer 5

1. Velocity
2. Displacement
3. Force
4. Weight
5. Acceleration

Question 6

What is velocity?

Answer 6

The speed of an object in a specific direction.

Question 6

Give examples of scalar quantities.

Answer 6

● Temperature
● Time
● Mass
● Speed
● Distance
● Energy

Question 7

On a distance/time graph, what value does the gradient of the line represent?s

Answer 7

speed

Question 8

Give an equation relating average speed, distance and time.

Answer 8

average speed = distance / time

Question 9

On a displacement/time graph, what value does the gradient of the line represent?

Answer 9

velocity

Question 10

What must be done to calculate speed at a given time from a distance-time graph for an accelerating object?

Answer 10

● Draw a tangent to the curve at the required time
● Calculate the gradient of the tangent

Question 11

State the equation for the average acceleration of an object. Give appropriate units.

Answer 11

Acceleration = (v-u)/t

Acceleration (m/s²), Velocity (m/s), Time (s)

Question 12

Give an equation relating final velocity with initial velocity, displacement and acceleration.

Answer 12

v2 = u2 + 2as

Question 13

How can the distance travelled by an object be calculated from a velocity-time graph?

Answer 13

It is equal to the area under the graph.

Question 14

On a velocity/time graph what does the gradient of the graph represent?

Answer 14

The acceleration.

Question 15

State a typical value for the speed of sound.

Answer 15

330 m/s

Question 16

Typical value for speed of light

Answer 16

3 x 10^8 m/s

Question 17

What is a typical value for human walking speed?

Answer 17

1.5 m/s

Question 18

What is a typical value for human running speed?

Answer 18

3 m/s

Question 19

What is a typical value for human cycling speed?

Answer 19

6 m/s

Question 20

Give an approximate value for the acceleration of an object in free fall under gravity near the Earth’s surface.

Answer 20

10 m/s²

Question 21

Light gates experiment (5)

Answer 21

● Set up two, one at start and one at end

● Measure distance between them

● As soon as the object passes through the first, it will measure the time taken to reach the second

● Then use speed= distance/time

● This is more accurate as removes reaction time and human error with a stopwatch

Question 22

How can you measure human reaction times?

Answer 22

● Using the ruler drop test
● Person A and B hold each end of a ruler with the 0 cm
mark at the bottom
● Person A drops the ruler without telling person B
● Person B catches it
● The distance travelled corresponds to their reaction
time

Question 23

Why is it important that the 0cm mark is at the bottom?

Answer 23

So you can obtain the distance directly without having to calculate it; otherwise, a zero error would need to be accounted for.

Question 24

What is the stopping distance of a vehicle equal to?

Answer 24

thinking distance + braking distance

Question 25

For a given braking distance, if the vehicle’s speed is increased, what can be said about its stopping distance?

Answer 25

The stopping distance is increased with an increase in speed.

Question 26

Give a typical range of values for human reaction time.

Answer 26

0.2 seconds - 0.9 seconds

Question 27

Give three factors which can affect a driver’s reaction time.

Answer 27

1. Tiredness
2. Drugs
3. Alcohol

Question 28

Give two factors which may affect braking distance.

Answer 28

1. Adverse (wet/icy) road conditions
2. Poor tyre/brake conditions

Question 29

Describe the energy transfers that take place when a car applies its brakes.

Answer 29

● Work is done by the friction force between the brakes and wheel
● Kinetic energy of the wheel is converted to heat and is dissipated to the surroundings
through the brake discs

Question 30

To stop a car in a given distance, if its velocity is increased, what must happen to the braking force applied?

Answer 30

The braking force must also be increased.

Question 31

State two consequences of a vehicle undergoing very large decelerations.

Answer 31

Kinetic energy converted to heat is very high causing brakes to overheat
2. Loss of control of the vehicle