Question

A man holds a 178N ball in his hand, with the forearm horizontal. He can support the ball in this position because of the flexor muscle force M, which is applied perpendicular to the forearm. The forearm weighs 22 N and has a center of gravity as indicated. Find (A) the magnitude of M and (B) the magnitude and direction of the forceapplied by the upper arm bone to the forearm at the elbow jount
---Elbow jont
-------------|----|-----|------------|
-------------|----|-----|------------|
----0.0510m==|____|_____|=0.0890m----|
-------------|---------0.330m--------|

Answer 1

The problem is worked out on page 10 of
http://www.phys.lsu.edu/classes/fall2007/phys2001-24/lecture19.pdf

where a better figure is shown.