A 17 kg child descends a slide 3.5 m high and reaches the bottom with a speed of 4.5 m/s. How much work was done by friction as the child goes down the slide?

Answer 1

PE = mg*h = 17*9.8*3.5 = 583.1 Joules.
KEo = 583.1 J. , No friction.

KE = 0.5m*V^2 = 8.5*4.5^2 = 172.1 J.,
With friction.

KE Lost = KEo-KE = 583.1-172.1 = 411 J.
= Work done by friction.