Motion Revision Set 1

An object is moving with uniform deceleration. Which statement describes its motion?

• Its rate of change of speed is decreasing.

• Its speed is constant.

• Its speed is decreasing.

• Its speed is increasing.

Answer explanation

Deceleration means negative acceleration

Which other quantity must be measured in order to calculate the average speed of the ball between point X and point Y?

• angle of slope

• diameter of ball

• distance between X and Y

• height of ramp

Answer explanation

average speed = distance travelled÷time taken

The speed-time graph shows the motion of a car.

At which time is its acceleration greatest?

• A

• B

• C

• D

Answer explanation

Acceleration = gradient of velocity (speed) time graph. Line is steepest at B

What is the value of the car’s acceleration between 6 s and 10 s?

• 0.50 m/s²

• 0.80 m/s²

• 1.25 m/s²

• 1.50 m/s²

Answer explanation

gradient = change in y (15-10)

÷ change in x (10-6)

A car of mass 1500 kg has a speed of 20 m/s. It accelerates until its speed is 25 m/s. What is the increase in the kinetic energy of the car?

• 19 kJ

• 38 kJ

• 170 kJ

• 340 kJ

Answer explanation

kinetic energy change = 0.5 x 1500 x(25² - 20²)

1kJ = 1000J

Look at the velocity-time graph for a car.

Which graph shows the correct distance-time graph for this car?

• 
• 
• 
• 

Answer explanation

Velocity = gradient of distance-time graph.

Only one graph has a decreasing gradient

Look at the graph of distance against time for an object.

What is the speed of the object?

• 0.5 m/s

• 2.0 m/s

• 4.0 m/s

• 8.0 m/s

Answer explanation

speed = gradient of distance-time graph

= change in y ÷ change in x

= 4m ÷ 2s = 2 m/s

Look at the velocity time graph.

Which of the following is the distance travelled between 0 and 6 seconds?

• 22.5 m

• 45.0 m

• 67.5 m

• 90.0 m

Answer explanation

Distance travelled = area under graph.

0-3 s: area of triangle = 1/2 x 3 s x 15 m/s = 22.5 m

3-6 s: area of rectangle = 3 s x 15 m/s = 45 m/s

0-6 s: total area = 22.5 m + 45 m = 67.5 m

The speed-time graph represents the motion of a car travelling along a straight level road.

Which statement describes the motion of the car?

• It accelerates and reaches a constant speed.

• It accelerates and then stops moving.

• It decelerates and then reaches a constant speed.

• It decelerates and then stops moving.

Answer explanation

increasing speed = acceleration

then horizontal line = constant speed

A train begins a journey from a station and travels 60 km in a time of 20 minutes. What is the average speed of the train?

• 3.0 m/s

• 5.0 m/s

• 50 m/s

• 60 m/s

Answer explanation

speed = (60 000 m ÷ (20 x60)s) = 50 m/s