Question

A 50 kg sphere is projected vertically up with a speed of 200ms. It rises to a height of 150. The energy used up in overcoming friction is

Answer 1

H = v^2/(2g) = 400/(2*9.81)=20.387 m.

But it has risen upto 12 m only.

An energy equivalent to mg(20.387 -12) is lost.

5*9.81 *8.387= 411.382J of energy is lost.