## Physics (10th Edition)

The magnitude of $\vec{M}$ is $1196N$ and its direction is to the left.
There are 2 forces acting on the arm: - The horizontal force $M$ that the person's flexor exerts on forearm, pointing to the left. - The tension in the test apparatus, which reads $T=190N$. It points to the right. Choose the rotation axis to be at the elbow joint. - For $M$, the lever arm is $0.054m$. - For $T$, the lever arm is $0.34m$. Because the arm is in equilibrium, $$0.054M=0.34T$$ $$M=\frac{0.34T}{0.054}=1196N$$