Momentum Practice Questions

State the unit of momentum.

A hockey ball of mass $0.16\ \mathrm{kg}$ travels along the ground at $25\ \mathrm{m/s}$.

Calculate the momentum of the hockey ball.

momentum = .............................................................. kg m/s

A laboratory trolley of mass $1.2\ \mathrm{kg}$ has a momentum of $1.8\ \mathrm{kg\ m/s}$.

Calculate the velocity of the trolley.

velocity = .............................................................. m/s

State what is meant by the inertial mass of an object.

A resultant force of $270\ \mathrm{N}$ acts on the go-kart. The go-kart accelerates at $4.5\ \mathrm{m/s^2}$.

Calculate the inertial mass of the go-kart.

inertial mass = .............................................................. kg

A second go-kart has a greater inertial mass than the first go-kart.

State what this tells you about the force needed to give it the same acceleration.

Calculate the total momentum of the two wagons before the collision.

total momentum = .............................................................. kg m/s

Calculate the velocity of the coupled wagons immediately after the collision.

velocity = .............................................................. m/s

State the assumption you made about external forces in your answer to (b).

State the total momentum of the two gliders before the spring is released, and give a reason for your answer.

Calculate the velocity of glider B after the spring is released.

State the direction of this velocity.

velocity = .............................................................. m/s

direction = ..............................................................

Calculate the momentum of the ball just before it hits the floor.

momentum = .............................................................. kg m/s

Calculate the average force exerted on the ball by the floor.

Use the equation

$$F = \frac{mv - mu}{t}$$

force = .............................................................. N

A student calculated the change in momentum of the ball to be $0.17\ \mathrm{kg\ m/s}$.

Explain why this value is not correct.

Calculate the average force exerted on the passenger as they are brought to rest.

Use the equation

$$F = \frac{mv - mu}{t}$$

force = .............................................................. N

Without an airbag, the same passenger would have been brought to rest by the dashboard in $0.080\ \mathrm{s}$.

Explain, using a calculation, why the airbag reduces the risk of serious injury to the passenger.

Describe an investigation the students could carry out to show that momentum is conserved when the trolleys are pushed apart.

The students find that the momentum of trolley P is slightly smaller than the momentum of trolley Q.

Give one reason for this.

Calculate the velocity of the car and van immediately after the collision.

velocity = .............................................................. m/s

Calculate the average force exerted on the van during the collision.

force = .............................................................. N

State the size of the average force exerted on the car during the collision and explain your answer.