# Torsion question can anyone help?

1. Sep 15, 2010

### scw1

Torsion question can anyone help???

1. The problem statement, all variables and given/known data
For a power transmission system, a solid steel shaft is required to transmit a torque of 2000 Nm. The limiting factor is that the twist of the shaft should not exceed 5 degrees for each metre of the shaft length. The shear modulus G is 75 GPa for this steel. What should be the minimum shaft diameter??

2. Relevant equations
The general bending formula
T/J=Tau/r=Gxtheta/L

3. The attempt at a solution
I tried to use the bending formula and come up with 14mm minimum diameter shaft

2. Sep 15, 2010

### rock.freak667

Re: Torsion question can anyone help???

Your equation is the torsion equation, but could you post your working, I don't have a calculator on hand to check your answer.

3. Sep 16, 2010

### nvn

scw1: Your equation in post 1 is correct, but your current answer is incorrect. Ensure you are using correct units, and ensure you are using the correct equation for J. Try again.