1) A pendulum consists of a 2 kg stone swinging on a 4 m long string
of negligible mass. The stone has a speed of 8 m/s when it passes its
lowest point. a) What is the speed of the rock when it is at an angle of
60 degrees to the vertical? b) What is the greatest angle with the vertical
that the string will make during the stone's motion?
Not really sure Just trying to do it with energy conservation..
The Attempt at a Solution
Well I figured out that at 60 degree's the height of the stone from the ground is 2m
Thne I figured I should use E = k+mgy ...
and came up with Einitial = (1/2)(2kg)(8m/s)^2 + (2kg)(-9.8m/s^2)(4m)
Efinal = (1/2)(2kg)(v)^2 + (2kg)(-9.8m/s^2)(2m)
Where to go Next... no clue