I am having trouble on the last 2 questions of the problem. I already have these

Question

I am having trouble on the last 2 questions of the problem. I already have these answers: -Amount of rotational kinetic energy in this person's arms and legs as he walks is 4.94J -Average angular velocity of his arms and legs is 1.05 rad/s If a person of mass M simply moved forward with speed V, his kinetic energy would be 1/2MV^2 . However, in addition to possessing a forward motion, various parts of his body (such as the arms and legs) undergo rotation. Therefore, his total kinetic energy is the sum of the energy from his forward motion plus the rotational kinetic energy of his arms and legs. The purpose of this problem is to see how much this rotational motion contributes to the person's kinetic energy. Biomedical measurements show that the arms and hands together typically make up 14.0% of a person's mass, while the legs and feet together account for 36.0% . For a rough (but reasonable) calculation, we can model the arms and legs as thin uniform bars pivoting about the shoulder and hip, respectively. In a brisk walk, the arms and legs each move through an angle of about

Explanation / Answer

A)

average anglar velocity = pi/3 rad/s

B)

rotational energy = Iw^2 / 2 sum for legs and arms = 1.631 J

C)

total energy = 73*5*5/(2*3*3) + 1.631 = 101.389 +1.631 =103.02

D)

percentage = 1.583%

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