# Homework Help: Balancing Forces

1. Oct 7, 2008

### edition

1. The problem statement, all variables and given/known data
"When a person's thighbone (femur) is broken, the muscles draw the broken parts so tightly together that the length of the healed leg is slightly shorter than its original length. In the past, a traction device (see diagram) was used to oppose the natural muscle tension, allowing the bone to heal properly. What is the magnitude and direction of the tension force applied to the femur if the mass of the leg is 3.75 kg?"

m1 = 3.75 kg
m2 = 5.00 kg

2. Relevant equations
F= ma

3. The attempt at a solution
At first I only considered the vertical force of gravity in each section and found that the legs there would be a tension in the string of 42 N but the leg would be moving 1.4m/s2 up. However, the answer is supposed to be 75 N
. I can understand that there is a force that opposes the tension in the muscles, but I am confused as to how the diagram displays this.​

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