Energy absorbed using Charpy Test

[nfbball9]

Homework Statement

What would be the energy absorbed if a 60-lb, 31.5-in pendelum was released from an angle of 50 degrees hit a test bar, then rose to an angle of 20 degrees after impact?

This is done using a Charpy Test

Homework Equations

Not sure where to begin

The Attempt at a Solution

Not sure where to begin

 

[lewando]

Look at this problem in terms of change in potential energy, PE1 at initial release, PE2 at maximum height after impact.