1. The problem statement, all variables and given/known data A 28.0 kg child slides down a long slide in a playground. She starts from rest at a height h1 of 24.00 m. When she is partway down the slide, at a height h2 of 15.00 m, she is moving at a speed of 8.00 m/s. Calculate the mechanical energy lost due to friction (as heat, etc.). 2. Relevant equations non conservative work = (final KE + final PE) - (initial KE + initial PE) 3. The attempt at a solution initial KE cancels since the child starts from rest so it'll be the sum of the final kinetic energy and potential energy minus the initial potential energy. I worked that out and got -1573.6 J but when I go to check the answer it's wrong and I keep reworking and getting the same answer, but for some reason it's wrong. Anyone know what I'm doing wrong?