posted by Anonymous on .
A 25kg child on a 2m long swing is released from rest when the swing supports make an angle of 30 degrees with the vertical. (a) Neglecting friction, find the child's speed at the lowest position. (b) If the speed of the child at the lowest position is 2m/s, what is the mechanical energy lost due to friction?
(b)What am I suppose to do for b?