I am just going to link this because I don't know how to draw a nice diagram like that and put it here. But essentially that is the question. More specifically I have problems with part d)
W= Fd = EkE (I used this to solve the question but I got it wrong.)
The Attempt at a Solution
Some answers suggest to use trigonometry to find the second deflection. However, how can we know that the angle of the second deflection is same as the angle of the arc?
I figure we need to do something with kinematics but I can't seem to figure it out.