ScienceClass 9CBSE
Q
A ball is dropped from a height of 10 m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back? (g = 10 m s–2).
A
Soln:
mgh=m×10×10= 100m joules
when 40% energy is reduced remaining energy will be 60mjoules Hence 60-m×10×h
H= -6m