Posted by **clueless** on Wednesday, November 10, 2010 at 7:10pm.

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.

- PHYSICS -
**Damon**, Wednesday, November 10, 2010 at 7:21pm
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)

- PHYSICS -
**clueless**, Wednesday, November 10, 2010 at 7:28pm
thanks!

- PHYSICS -
**clueless**, Wednesday, November 10, 2010 at 7:35pm
If the speed of the child at the lowest position is 2.50 m/s, what is the mechanical energy lost due to friction?

- PHYSICS -
**bobpursley**, Wednesday, November 10, 2010 at 7:39pm
mechanical energy lost= PE at top-1/2 m vb^2 where vb is the speed at the bottom

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