## Physics: Principles with Applications (7th Edition)

We sum the torques about the elbow to solve for the force that the bicep muscle exerts on the forearm. Therefore; $(+ \circlearrowleft) \sum \tau=0$ $\sin105^{\circ}*F*.05m-2.0kg*9.8m/s^2*.15m-25kg*9.8m/s^2*.35m=0$ $F=(2.0kg*9.8m/s^2*.15m+25kg*9.8m/s^2*.35m)/(\sin105^{\circ}*0.05m)$ $F\approx1800N$ The max force the bicep muscle exerts on the forearm is about 1800N.