posted by Katie .
A wire is frictionless between points A and B and rough between B and C. A is 5m above the ground, B is zero, and C is 2m above the ground. The 0.400kg bead starts from rest at A. If the bead comes to rest at C, find the loss in mechanical energy as it goes from B to C.
I can't figure out how to find mechanical energy and can't even find an equation in my book.