Question

A ball is dropped from a height of 10m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back ? (g  10ms2

Answer 1

the ball has a potetial energy = mgh
when the ball is dropped it gets chamged to kinetic energy and when it strikes the ground it again gets converted to potential energy and loses 40 percent of the energy and therefore energy left will be = mgh-40 percent of mgh

Now, the new mgh = m100-0.4*m*100
10h = 100-40
h=6
therefore the height that it will attain after striling the ground is 6m.