A 27.0 kg child on a 3.00 m long swing is released from rest when the swing supports make an angle of 31.0° with the vertical. Neglecting friction, find the child's speed at the lowest position.

Answer 1

mass is irrelevant for pendulum, cancels
Figure out how high the child is above the low point when the chains are 31 deg from vertical
h = 3 (1 - cos 31)
U at top = m g h
Ke at bottom = U at to
(1/2) m v^2 = m g h
v = sqrt (2 g h)

Answer 2

thanks!

Answer 3

If the speed of the child at the lowest position is 2.50 m/s, what is the mechanical energy lost due to friction?

Answer 4

mechanical energy lost= PE at top-1/2 m vb^2 where vb is the speed at the bottom