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December 20, 2014

December 20, 2014

Posted by **Justin** on Sunday, October 8, 2006 at 3:30pm.

A 28.0 kg child plays on a swing having support ropes that are 1.90 m long. A friend pulls her back until the ropes are 45.0 degrees from the vertical and releases her from rest.

What is the potential energy for the child just as she is released, compared with the potential energy at the bottom of the swing?

Answer expressed in J.

How fast will she be moving at the bottom of the swing?

Answer expressed in m/s.

How much work does the tension in the ropes do as the child swings from the initial position to the bottom?

Answer expressed in J.

Draw the figure. What is the height of the child? (I think it is 1.90-1.90cos45, check that)

PE = mgh

KE at bottom= 1/2 mv^2 which will equal the max PE at the top.

Work in tension? Do the ropes stretch? Work is only done by a force if it travels in the direction of the force.

- Physics -
**Anonymous**, Thursday, November 20, 2008 at 2:04pmthe tension is 0

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