1] Matthew holds a 50 lbs dumbbell in his hand with his elbow flexed at 90 degre

Question

                    1] Matthew holds a 50 lbs dumbbell in his hand with his elbow flexed at 90 degrees. His forearm is                                                       parallel with the ground. The resultant distance from the dumbbell to his elbow is 28 cm.                                                       a.What is the torque created by the dumbbell about the elbow joint?                                                       b.What torque must be created by the elbow flexor muscles to hold the weight still?                                                       
                    2)Matthew holds a 50 lbs dumbbell in his hand with his elbow flexed at 90 degrees. His forearm is                                                       at a 45 degree angle with the horizontal (elbow angle is 135 degrees) with the ground. The                                                       resultant distance from the dumbbell to his elbow is 28 cm.                                                       a.What is the torque created by                                                       the dumbbell about the elbow joint?                                                       b.What torque must be created by the elbow flexor muscles to hold the weight still?                                                       
                    3)Matthew holds a 50 lbs dumbbell in his hand with his elbow flexed at 90 degrees. His forearm is                                                       parallel with the ground. The resultant distance from the dumbbell to his elbow is 28 cm.                                                       a.What is the torque created by the dumbbell about the elbow joint?                                                       b.If the weight is held still, and the moment arm of the biceps to the elbow is 2 cm, how                                                       much force is developed with the biceps?                                                       
                    4)A person lies on a balance board as shown in the figure below. The person weights 80 kg, and                                                       the scaleunder the person                     1] Matthew holds a 50 lbs dumbbell in his hand with his elbow flexed at 90 degrees. His forearm is                                      parallel with the ground. The resultant distance from the dumbbell to his elbow is 28 cm.                                      a.What is the torque created by the dumbbell about the elbow joint?                                      b.What torque must be created by the elbow flexor muscles to hold the weight still?                                      
                    2)Matthew holds a 50 lbs dumbbell in his hand with his elbow flexed at 90 degrees. His forearm is                                      at a 45 degree angle with the horizontal (elbow angle is 135 degrees) with the ground. The                                      resultant distance from the dumbbell to his elbow is 28 cm.                                      a.What is the torque created by                                      the dumbbell about the elbow joint?                                      b.What torque must be created by the elbow flexor muscles to hold the weight still?                                      
                    3)Matthew holds a 50 lbs dumbbell in his hand with his elbow flexed at 90 degrees. His forearm is                                      parallel with the ground. The resultant distance from the dumbbell to his elbow is 28 cm.                                      a.What is the torque created by the dumbbell about the elbow joint?                                      b.If the weight is held still, and the moment arm of the biceps to the elbow is 2 cm, how                                      much force is developed with the biceps?                                      
                    4)A person lies on a balance board as shown in the figure below. The person weights 80 kg, and                                      the scaleunder the person

Explanation / Answer

1)
50 lb = 0.454*50 = 22.7 N

r is perpendiicular distance
a) Torque, T = r*F*sin(90) = 0.28 *22.7 = 6.356 N.m
b) same 6.356 N.m

2)
a) Torque, T = r*F*sin(45) = 0.28 *22.7 = 4.493 N.m
b) same 4.493 N.m


3)

a) Torque, T = r*F*sin(90) = 0.28 *22.7 = 6.356 N.m

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