A student drops a 0.011 kg super ball from a height of 1 m. If the ball returns to a height of .75 m, how much mechanical energy was lost to dissipative forces?
in your case: 0.011(9.8)(0.25) Joules
There is only gravitational potential energy at the very begining and the very end. The difference, mg(hf-hi), in gravitational potential energy from beginning to end must have left the system (a.k.a. lost or dissipated)