Question

A ball of mass


0.1kg,


starting from rest, falls a height of 4.0 m and then collides with


the ground. After the collision, the ball bounces up to a height of 2.0 m. The collision


with the ground takes place over a time


4.0 10 s.


3





Determine (i) the momentum of


the ball immediately before the collision and immediately after the collision and (ii) the


average force exerted by the ground on the ball. Take


10.0 ms .

Answer 1

$p_1=m\sqrt{2gh_1}$ , $p_2=m\sqrt{2gh_2}$ , $\bar{F}=\frac{p_1+p_2}{t}$ ,hence $p_1=0.1\sqrt{2\sdot 10\sdot 4}\approx0.90kg\sdot m/s$ , $p_2=0.1\sqrt{2\sdot 10\sdot 2}$ $\approx0.63kg\sdot m/s$ , $\bar{F}=\frac{0.9+0.63}{0.1}\approx15.3N$