# Homework Help: Total work done on a screw.

1. Apr 19, 2010

### smhippe

1. The problem statement, all variables and given/known data
It takes 20 turns to drive a screw completely into a block of wood. Because the
friction force between the wood and the screw is proportional to the contact area between
the wood and the screw, the torque required for turning the screw increases linearly with
the depth that the screw has penetrated into the wood. If the maximum torque is 12 N m
when the screw is completely in the wood, what is the total work (in Joules) required to
drive in the screw?

3. The attempt at a solution
So I tried to do an integral by finding out how much the torque changed per rotation. Then using that as the equation and the total distance turned to be plugged in.
$$\int.6x$$ from 0 to 7200. I got a very large number and I don't think I did it right....