SELECTED PROBLEMS TO COMPLETE

8. How much tension (F_{m = Moment of Force}) must be supplied by the triceps to stabilize the arm against an external force (Fe) of 200 N, given d_{m (distance arm)} = 2 cm, and d_{e (wt. arm)} = 25 cm as shown in the textbook? What is the magnitude of the joint reaction force (R)? (Since the forearm is vertical, its weight does not produce torque at the elbow.) (F_m = 2500 N, R = 2700 N)

            For a state of equilibrium, T_m = T_e  or

Formula: (Fm x Force Arm = Wt. x Wt. Arm)           

            F_m = ______________

            Joint Reaction Force Formula: R = F_m + F_e

            R = _______________

9. What is the length of the moment arm between the dumbbell and the shoulder when the extended 50 cm arm is positioned as shown in the text?

          Formula (or vertical component):  MA = sin 60° · 50 cm = ___________________

10. The medial deltoid attaches to the humerus at an angle of 15° as shown in the text. What are the sizes of the rotary and stabilizing components of muscle force when the total force is 500 N?

Rotary Formula (or Vertical Component): F_R = 500 N · sin 15° = _________________

Stabilizing Formula (or Horizontal Component): F_S = 500 N · cos 15° = _________________