Physics help?? should be easy??

Question

An arm makes a 37 degree angle with the horizontal and a torque of 18 m * N is to be produced what is the force the bicep muscles must supply?

Answer: 560 N from back of the book, but how?

Answer 1

Torque is a force times a distance. I think your problem is missing a length of the arm - you need that to solve this one.

Once you get that, and assuming that you're pulling straight up on something, you can find the force through a torque equation, T = Fd. The only other trick is that the force we need to calculate isn't tangent to the circle created by the pivot - the force (again, I'm assuming you're pulling straight up), actually acts at an angle. So the formula will have to be modified to T = Fd * cos37 to account for the angle.

We have the torque, but again we're missing the distance. But once you have that, you can calculate your force, which should turn out to be 560 N.