(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A schematic diagram of the human arm is shown holding a

heavy iron ball (mass 5.0 kg). The triceps muscle connects to the

forearm 3.0 cm to the left of the elbow joint, while the biceps

muscle connects 5.0 cm to the right. Each of the muscles can

exert an upward force on the forearm when needed. The

forearm and hand together itself have a mass of 4.0 kg and a

center of mass 15 cm to the right of the elbow joint. The distance from the triceps

to the center of the ball is 35 cm

a. When the ball is being held as shown, the force exerted by

the triceps is approximately zero. What force must the

biceps be exerting?

2. Relevant equations

For this problem I attempted to use sigma torque equation to find how much force is needed for the bicep to hold the ball up.

3. The attempt at a solution

I found the forces drawing a free body diagram to be

force of bicep, force of ball, force of arm, and force of triceps.

so force of biceps = (5.0 x 9.8N) - (15 cm x 9.8N) - (3.0 x 9.8)

I feel like Im still missing a big chunk in my equation, but I seem to be having trouble with these torque problems any advice on how to solve them? =X

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# Homework Help: Torque problem involving bicep holding ball

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