A 395 N child is in a swing that is attached to ropes 1.8 m long. Find the gravitational potential energy of the child+Earth system relative to the child's lowest position when the ropes make a 30° angle with the vertical.(adsbygoogle = window.adsbygoogle || []).push({});

What I did with this problem is I drew a diagram and then figured that y would be 1.8cos30

U=mgy

U=395(1.8cos30)= 6.16e2 J

Is there anything that I did wrong with this problem it's confusing me with the angle. I feel like there's more to do than this but I'm not sure what.

Thanks for any help

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Gravitational Potential Energy of a swing

**Physics Forums | Science Articles, Homework Help, Discussion**