- #1
sireh
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Homework Statement
A 400-N child is in a swing that is attached to a pair of ropes 2.00 m long. Find the gravitational potential energy of the child-Earth system relative to the child’s lowest position when
(b) the ropes make a 30.0° angle with the vertical
Homework Equations
Ug=mgy
The Attempt at a Solution
b.) Ug = 400N ⋅ 2m(1-cos30)
Ug = 107J
I understand everything about the problem (and was able to do the other parts of it without issue) except where the 1-cos30 comes from. Even drawing it out I just can't visualize where that is coming from. I originally thought that it would just be 2m(cos30) but the answer key says that is wrong.