A man holds a 197-N ball in his hand, with the forearm horizontal (see the figure). He can support the ball in this position because of the flexor muscle force , which is applied perpendicular to the forearm. The forearm weighs 19.4 N and has a centre of gravity as indicated. Find (c) direction (as a positive angle counterclockwise from horizontal) of the force applied by the upper arm bone to the forearm at the elbow joint.
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Answer:
22. �A man holds a 178-N ball in his hand, with the forearm horizontal (see the drawing). He can support the ball in this position because of the flexor muscle force , which is applied perpendicular to the forearm. The forearm weighs 22.0 N and has a center of gravity as indicated. Find (a) the magnitude of �and (b) the magnitude and direction of the force applied by the upper arm bone to the forearm at the elbow joint.
Take the torques about the elbow joint.� This way the force of the upper arm has no lever arm and will therefore have no torque about elbow joint.
Answer:
A man holds a 197-N ball in his hand, with the forearm horizontal (see the figure). He can support the ball in this position because of the flexor muscle force , which is applied perpendicular to the forearm. The forearm weighs 19.4 N and has a centre of gravity as indicated. Find (c) direction (as a positive angle counterclockwise from horizontal) of the force applied by the upper arm bone to the forearm at the elbow joint.