# Archived Forces in achilles and foot bone

1. Oct 23, 2013

### tristanmagnum

1. The problem statement, all variables and given/known data
The Achilles tendon is attached to the rear of the foot as shown in (Figure 1) . A person elevates himself just barely off the floor on the "ball of one foot." Assume the person has a mass of 80kg and D is twice as long as d.

a:Find the tension FT in the Achilles tendon (pulling upward).
b:Find the (downward) force FB exerted by the lower leg bone on the foot.

http://session.masteringphysics.com/problemAsset/1706786/4/GIANCOLI.ch09.p34.jpg

2. Relevant equations

FB + FT -m*g = 0 [Force Equilibrium]
FB*D + FT*(D+d) = 0 [Moment Equilibrium]

i think

3. The attempt at a solution

not sure what to do because there doesn't seem to be enough info.

2. Feb 5, 2016

### OrangeDog

Model the foot as a beam with the end opposite of the tendon as a cantilever. There is plenty of info to solve the problem. Unfortunately your moment equation is incorrect which is causing problems. And remember to use the right hand rule.