A pendulum consists of a small object hanging from the ceiling at the end of a string of negligible mass. The string has a length of 0.88 m. With the string hanging vertically, the object is given an initial velocity of 1.7 m/s parallel to the ground and swings upward on a circular arc. Eventually, the object comes to a momentary halt at a point where the string makes an angle θ with its initial vertical orientation and then swings back downward. Find the angle θ.

Answer 1

mv²/2= mgh=mgL(1-cosθ)
cosθ= 1- (v²/gL)
θ=arccos[1- (v²/gL)]

Answer 2

This doesn't give me the correct answer according to the assignment program :/