This seems like it should be easy but Im not sure what to do. Heres the problem: 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!!!