(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The figure shows a person whose weight is W = 725 N doing push-ups. Find the normal force exerted by the floor on (a)each hand and (b)each foot, assuming that the person holds this position.

2. Relevant equations

center of gravity = cg

Xcg = (W1x1 + w2x2 +...)/(w1 + w2...)

net torque = w1x1 + w2x2 +...

3. The attempt at a solution

Placing the axis of rotation at the far left gives:

W1(0) + W2(.84) + W3(1.25) / 725 = .84

Placing it at the far right gives:

W1(1.25) + W2(.41) + W3(0) / 725 = .41

Solving these yields W1 = [297.25 - W2(.41)]/1.25

or

W2 = 297.25 - W1(1.25)

and

W2(.84) + W3(1.25) = 609

However, there are still too many unknowns. Where do I take it from here?

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# Homework Help: Finding normal force from center of gravity

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