A 20kg child slides down a long slide in a playground. She starts from rest at a height of 25m. When she is part way down the slide at a height of 10m, she is moving at 16m/s. Calculate the mechanical energy lost due to friction.

Answer 1

PEmax = mg*hmax - FE
PEmax = 20*9.8*25 - FE = (4900-FE) J.

KE + PE = 4900 - FE
0.5m*V^2 + mg*h = 4900-FE
10*16^2 + 196*10 = 4900-FE
2560 + 1960 = 4900-FE
4520 = 4900-FE
FE = 4900-4520 = 380 J. = Energy loss
due to friction.