Question

A ball of mass 1000kg is dropped from a height of 5m and rebounded to a height of 25cm calculate:(I) it's kinetic energy just before impact (ii) its initial rebounce velocity and kinetic energy

Answer 1

(i) it's kinetic energy just before impact:

$$KE=mgh=49000\text{ J}.$$

(ii) its initial rebounce velocity and kinetic energy

$$v_r=\sqrt{2gh}=2.21\text{ m/s}.\\\space\\ KE_r=\dfrac 12mv_r^2=2442\text{ J}.$$