To strengthen his arm and chest muscles, an 78.8kgathlete 1.81m tall is doing a

Question

To strengthen his arm and chest muscles, an 78.8kgathlete 1.81m tall is doing a series of push-ups. His center of mass is 1.17m from the bottom of his feet, and the centers of his palms are 30.2cm from the top of his head. Find the force that the floor exerts on each of his feet and on each hand, assuming that both feet exert the same force and both palms do likewise.

a) Find the force that the floor exerts on each of his feet, assuming that both feet exert the same force. Use the numbers given in the problem instead of from the picture to do this problem.

b) Find the force that the floor exerts on each of his hand, both palms exert the same force.

Explanation / Answer

Part A)

Place the pivot point at the hands and solve by torques...

Fr = Fr

2(F)(1.81 - .302) = (78.8)(9.8)(1.81 - .302 - 1.17)

F = 86.5 N each foot

Part B)

Now solve this part by the sum of forces...

(2)(86.5) + 2F = (78.8)(9.8)

F = 299.6 N each hand

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