An athlete at the gym holds a 1.2 kg steel ball in his hand. His arm is 64 cm long and has a mass of 4.0 kg. What is the magnitude of the torque about his shoulder if he holds his arm in each of the following ways?

Question

1. straight but 30 degrees below horizonal?

Answer 1

Torque = force*length*sinTheta
= 1.2*9.8*.64*sin60

the angle theta is the angle between the force and the arm.