5. (3 points) During therapy for a shoulder injury, a client performs an isometr

Question

5. (3 points) During therapy for a shoulder injury, a client performs an isometric exercise against a resistance of 70 N, as shown in the figure below. A diagram of the forces and torques acting on the client's arm in the frontal plane is shown in the figure on the right. The arm is not moving. a. What is the magnitude and direction of the resultant shoulder torque (Ts) needed to keep the arm from rotating? You must say whether the resultant torque is acting counterclockwise or clockwise based on your anterior view of the patient. Based on your answer to part (a), which muscle group must be active during this exercise? (Note: assume that muscles are the only contributors to Ts) The shoulder abductors (e.g. middle deltoid) LThe shoulder adductors (e.g. latissimus dorsi, teres major) 62 cm FR KFR 33 cm 1300 shoulder N 21° hand 90° Ts - Fs y (upward) X (medial) Fs = resultant shoulder force = 48.2 N TS = resultant shoulder torque FR = resistance force = 70 N Fw = arm weight = 36.3 N

Explanation / Answer

a)

resultant should torque is given as

Ts = Fs (0.33) Sin21

Ts = (48.2) (0.33) Sin21 = 5.7 Nm

direction : counterclockwise.

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