PHYS 1145 Midterm Exam Spring 201'? Name: Problem 4 (25 points). The extensor muscle in the upper arm exerts force, F M, on the lower arm in order to support a M=5kg ball. Assume that the lower arm has the mass of m=2.6 kg and its center of gravity is 13cm from the elbow-j oint pivot (as shown). a. (5 points) Calculate the torque about joint due to the weight of the lower arm alone (indicate the direction as clockwise or counterclockwise). b. (5 points) What is the torque about joint due to the weight of the ball (indicate the direction as clockwise or counterclockwise)? c. (5 points) Using torque equilibrium equation nd the force FM exerted by the extensor muscle