Topic 1.6: Momentum

Which of the following terms and equations are equivalent to the change in an object's momentum?

• A

• B

• C

• D

A ball with mass of 5.0 kg is moving with a velocity of 3.0 m/s.

What is the momentum of the ball?

• 0.6 kgm/s

• 1.70 kgm/s

• 15 kgm/s

• 15 000 kgm/s

A ball which has momentum = 30 kg m/s hits a stationary ball with momentum = 0 kgm/s so that they both move off .

What is the total momentum of the two balls following the collision?

• 0 kgm/s

• 3 kgm/s

• − 30 kgm/s

• 30 kgm/s

A footballer kicks a ball with a force of 1500 N. Her foot is in contact with the ball for 1.4seconds.

What is the impulse on the ball?

• 1070 Ns

• 2100 Ns

• 3000 Ns

• 4200 Ns

A rollercoaster moving along a track has a large momentum.

A second rollercoaster has half the mass of the first rollercoaster and travels at four times the speed.

What is the momentum of the second rollercoaster compared to the first?

• The second rollercoaster has a momentum of zero

• The second rollercoaster's momentum is half that of the first rollercoaster's momentum

• The second rollercoaster's momentum is twice that of the first rollercoaster's momentum

• The second rollercoaster's momentum is four times that of the first rollercoaster's momentum

A gas molecule strikes the wall of a container with a speed of 200m/s. It rebounds with the same kinetic energy as it had before striking the wall.

What is its final velocity?

• 100 m/s

• - 100 m/s

• 200 m/s

• - 200 m/s

Padded dashboards in cars are safer in an accident than non-padded ones because a passenger hitting the dashboard would experience

• Lengthened time of contact

• Shorter time of contact

• Decreased impulse

• Increased momentum

After a car crash the car driver's airbag infl ates. The airbag then defl ates when it is hit bythe driver’s head.

How does an airbag reduce the risk of injury?

• Collision time increases, which increases the rate of change of momentum

• Collision time increases, which reduces the rate of change of momentum

• Collision time decreases, which increases the rate of change of momentum

• Collision time decreases, which reduces the rate of change of momentum

An object of mass 150 kg accelerates from a velocity of 5 m/s to a velocity of 10 m/s in the same direction.

What is the impulse provided to cause this acceleration?

• 750 Ns

• 1500 Ns

• 2250 Ns

• 7500 Ns

A passenger of mass 90 kg is involved in a minor car crash.

The car approaches a solid barrier at 32 m/s. It crashes into the barrer and stops in 0.2s.

Determine the impulse that must be applied to the car to bring it to rest.

• 2.8 Ns

• 14 Ns

• 580 Ns

• 2900 Ns