P9

Question 1

What is acceleration?

Answer 1

The rate of change of velocity (in metres per second per second, m/s²).

Question 2

What is deacceleration?

Answer 2

The rate of change of velocity when an object slows down.

Question 3

What is displacement

Answer 3

Distance given in a direction

Question 4

What is the gradient?

Answer 4

Change of the quantity plotted on the y-axis divided by the change of the quantity plotted on the x-axis.

Question 5

What is the tangent?

Answer 5

A straight line drawn to touch a point on a curve so it has the same gradient as the curve at that point.

Question 6

What is velocity?

Answer 6

Speed in a given direction (in metres per second, m/s).

Question 7

Distance-time graph

Answer 7

The gradient of this kind of graph represents the speed of an object.

Question 8

Vector

Answer 8

A physical quantity that has direction as well as magnitude. e.g. velocity.

Question 9

Scalar

Answer 9

A physical quantity that has magnitude, but not direction. e.g. speed.

Question 10

What does S stand for in SUVAT?

Answer 10

Distance travelled

Question 11

What does U stand for in SUVAT?

Answer 11

Intial velocity

Question 12

What does V stand for in SUVAT?

Answer 12

Final velocity

Question 13

What does A stand for in SUVAT?

Answer 13

Acceleration

Question 14

What does T stand for in SUVAT?

Answer 14

Time taken

Question 15

Does a distance quantity require a specific direction?
i.e. is it a scalar or vector quantity?

Answer 15

No specific direction is required so it is a scalar quantity.

Question 16

If an object moves 3 metres to the left and then 3 metres back to its initial position, what is the object’s total displacement?

Answer 16

• The object has zero displacement
• Displacement is a vector quantity so it also involves direction
• The object starts and ends at the same point

Question 17

State a typical value for the speed of sound

Answer 17

330 m/s

Question 18

What is a typical value for human walking speed?

Answer 18

1.5 m/s

Question 19

What is a typical value for human running speed?

Answer 19

3 m/s

Question 20

What is a typical value for human cycling speed?

Answer 20

6 m/s

Question 21

State the equation linking distance, speed and time.
Give appropriate units.

Answer 21

Distance = Speed × Time
Distance (m), Speed (m/s), Time (s)

Question 22

Why can an object travelling at a constant speed in a circle not have a constant velocity? (Higher)

Answer 22

• Speed is a scalar quantity
• Velocity is a vector quantity which means it can only be constant if the direction is constant
• In circular motion, the direction is continuously changing

Question 23

How can speed be calculated from a distance-time graph?

Answer 23

The speed is equal to the gradient of the graph.

Question 24

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

Answer 24

• Drawing a tangent to the curve at the required time
• Calculating the gradient of the tangent

Question 25

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

Answer 25

Acceleration = (Change in Velocity)/(Time
Taken)
Acceleration (m/s?), Velocity (m/s), Time (s)

Question 26

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

Answer 26

It is equal to the area under the graph.

Question 27

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

Answer 27

9.8 m/s?

Question 28

What can be said about the resultant force acting on an object when it is falling at terminal velocity?

Answer 28

• The resultant force is zero
• When at terminal velocity, the object is moving at a constant speed and so isn’t accelerating

Question 29

State Newton’s first law for a stationary object.

Answer 29

If the resultant force on a stationary object is zero, the object will remain at rest.

Question 30

State Newton’s first law for a moving object.

Answer 30

If the resultant force on a moving object is zero, the object will remain at constant velocity (same speed in same direction).

Question 31

What can be said about the braking forces and driving forces when a car is travelling at constant velocity?

Answer 31

The braking forces are equal to the driving forces.

Question 32

If an object changes direction but remains at a constant speed, is there a resultant force?

Answer 32

Since there is a change in direction, there is a change in velocity and so there must be a resultant force.