David Sang and Graham Jones Solutions for Chapter: Momentum, Exercise 8: Questions

A car of mass $1000 \mathrm{kg}$ is travelling at a velocity of $+10 \mathrm{m}{\mathrm{s}}^{-1}$. It accelerates for $15 \mathrm{s}$, reaching a velocity of $+24 \mathrm{m}{\mathrm{s}}^{-1}$. Calculate:

(a) The change in the momentum of the car in the $15 \mathrm{s}$ period

A car of mass $1000 \mathrm{kg}$ is travelling at a velocity of $+10 \mathrm{m}{\mathrm{s}}^{-1}$. It accelerates for $15 \mathrm{s}$, reaching a velocity of $+24 \mathrm{m}{\mathrm{s}}^{-1}$ 

Calculate the average resultant force acting on the car as it accelerates.

A ball is kicked by a footballer. The average force on the ball is $240 \mathrm{N}$ and the impact lasts for a time interval of $0.25 \mathrm{s}$

 Calculate the change in the ball's momentum.

A ball is kicked by a footballer. The average force on the ball is $240 \mathrm{N}$ and the impact lasts for a time interval of $0.25 \mathrm{s}$

(b) State the direction of the change in momentum.

Water pouring from a broken pipe lands on a flat roof. The water is moving at $5.0 \mathrm{m}{\mathrm{s}}^{-1}$ when it strikes the roof. The water hits the roof at a rate of $10 \mathrm{kg}{ \mathrm{s}}^{-1}$ Calculate the force of the water hitting the roof. (Assume that the water does not bounce as it hits the roof. If it did bounce, would your answer be greater or smaller?)

A golf ball has a mass of $0.046 \mathrm{kg}$. The final velocity of the ball after being struck by a golf club is $50 {\mathrm{ms}}^{-1}$. The golf club is in contact with the ball for a time of $1.3 \mathrm{ms}$. Calculate the average force exerted by the golf club on the ball.