The Roller Ball skate is an in-line tandem skate that uses two large spherical wheels on each

Question:

The Roller Ball skate is an in-line tandem skate that uses two large spherical wheels on each skate, rather than traditional wafer-shape wheels. During skating the two forces acting on the wheel of one skate consist of a normal force F2 and a friction force F1. Determine the moment of both of these forces about the axle AB of the wheel.

Given:
θ = 30 deg
F1 = 13 lb
F2 = 78 lb
a = 1.25 in

F1 F2