Originally Posted by

**JAlberts**
Assuming you used consistent units, quick combing of the basic equations for Jm (Polar Moment of inertia) for a tube and T (torque, Nm) indicates that your equation is generally correct except for one issue. For a tube about its central axis: Jm = 1/2M(R^{2}+ r^{2}) which would revise your formula to T = 1/2M(R^{2}+ r^{2})a

For your reassurance on your equation calculation, by calculating the two rotational velocities used to determine the rotational acceleration value in radians/sec gives me (377-52.4)/2.4 = 135.25 radians/sec^2 and using that in your equation my solution is also: T = 1.8 x 135.25 x (.045/2)^2 = .123 Nm, so all other quantities kept equal, using the above revised equation should obtain a correct value for your solution.