Physics
posted by Ben on .
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.

mv²/2= mgh=mgL(1cosθ)
cosθ= 1 (v²/gL)
θ=arccos[1 (v²/gL)]
θ=arccos[1 (1.7²/9.8•0.88)] = 34.6° 
Should be 2gL