This seems like it should be easy but Im not sure what to do. Heres the problem:(adsbygoogle = window.adsbygoogle || []).push({});

The picture to the problem is here: http://www.webassign.net/giancoli/9-65alt.gif

"(a) Calculate the magnitude of the force FM required of the "deltoid" muscle to hold up the outstretched arm shown in Fig. 9-65. The total mass of the arm is 2.8 kg and = 12°.

(b) Calculate the magnitude of the force FJ exerted by the shoulder joint on the upper arm.

I found a) by doing .12 m (sin 12) F - .25 m (2.8 kg) (9.8 m/s^2) = 0. F = 264 N.

But how do I find the force FJ? Confused (we haven't had the lesson on this yet, but trying to get my homework done early because I have a busy week). THANKS for any help!!!

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# Equilibrium when applied to muscles and joints! Help, please!

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