Gail tries to perform an standing arm curl with a 12 lb. dumbbell. (1 lb = 0.453
ID: 1509498 • Letter: G
Question
Gail tries to perform an standing arm curl with a 12 lb. dumbbell. (1 lb = 0.453 kg). The distance between the olecranon and the metacarpals of the hand is 10.6 inches. The biceps muscle inserts 0.04 m from the olecranon. The forearms are light, so we can ignore their mass for now. Using good form, the humerus stays vertical. When the forearm is parallel to the ground so that the elbow is at 90 degrees, how much rotary force is being produced by the muscle? (answer in N) The answer was 359 N . How was this calculated?
Explanation / Answer
Balancing Torque we have;
F*0.04 = mgL
F*0.04 = 12*0.453*9.81*0.2692
F = 14.3557/0.04 = 358.89 N
F = 359 N
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