Momentum

A safety test was carried out to determine how the speed of a car affects the stopping distance of the car.

At the start of the test the car was moving slowly.

Then the car accelerated at 5.8 m/s² for 2.5 s.

The final velocity of the car was 20 m/s.

Calculate the initial velocity of the car.

Use the Physics Equations Sheet.

The reaction time of the driver was measured.

How can the reaction time of the driver be used to calculate the thinking distance?

The car was driven at a constant speed. The driver applied the maximum braking force, and the braking distance was measured.

The test was repeated at different speeds.

Figure 8 shows the results.

Which of the following gives the relationship between the speed and the braking distance?

Tick () one box.

During one test the brakes were applied with a force of 6250 N.

The deceleration of the car was 5.0 m/s².

The braking distance of the car was 14.4 m.

Determine the momentum of the car before the brakes were applied.

Use the Physics Equations Sheet.

Use Figure 8.

Momentum = kg m/s

Figure 4 shows a child playing with a toy train. The train is on a bridge.

When the child lets go of the train, the train rolls down the bridge.

The momentum of the train at the bottom of the bridge is 0.216 kg m/s mass of the train = 180 g Calculate the velocity of the train at the bottom of the bridge. Use the Physics Equations Sheet.

The train collides with a stationary carriage on the track. Explain why the velocity of the train after the collision is less than it was before the collision. Use ideas about momentum in your answer.

Figure 8 shows a girl bowling a ball along a ten-pin bowling lane.

The girl is trying to knock down the ten pins at the end of the bowling lane.

Velocity is a vector quantity, speed is a scalar quantity. Describe what is meant by a vector quantity and a scalar quantity.

The bowling lane is horizontal. Explain why the bowling ball decelerates as it travels along the lane.

Figure 9 shows the bowling ball hitting one of the pins.

Write down the equation that links mass (m), momentum (p) and velocity (v).

The bowling ball has a velocity of 5.0 m/s when it hits the pin. The momentum of the bowling ball is 26 kg m/s Calculate the mass of the bowling ball.

Explain why the bowling ball slows down when it hits the pin. You should use ideas about momentum in your answer.

Some quantities are scalars and some are vectors.

Which of the following quantities are scalars?

Tick (✓) two boxes.

Give the difference between a vector quantity and a scalar quantity.

Bumper cars are a fairground ride and are designed to bump into each other.

Figure 5 shows two bumper cars moving towards each other.

The momentum of each bumper car is shown by an arrow.

Give two factors that affect the momentum of each bumper car.

The bumper cars crash into each other and stop.

Explain why both bumper cars stop after the crash.

Figure 5 shows an ice skater, Skater A.

Write down the equation that links mass, momentum and velocity.

Skater A travels with a velocity of 3.2 m/s and has a momentum of 200 kg m/s Calculate the mass of Skater A.

Skater A bumps into another skater, Skater B. Skater B is stationary. The skaters move off together in a straight line. Explain what happens to the velocity of each of the skaters. Use the idea of conservation of momentum.