Stuck on inertia / angular velocity / torque calculation

[Slikatel]

Hello all and thanks for viewing this, I am in need of some assistance to solve a problem to size an AC motor rotating this load (power transmission will be trough belt & pulley).

I have a hollow cylinder (pipe) that needs to spin 25 RPM:

- OD = 50 mm
- ID = 48 mm
- M = 200 kg
- Total length = 40m

The formula for inertia (Z-axis) i found when searching for a hollow cylinder = I = M * r^2 this gives me a solution of I = 0.1201 kg/m²

If i put this in the torque formula of T = I x angular acceleration = 0.1201 kg/m² x 2.618 rad/s2 (25RPM - 1 sec - ) = 0,3144218 Nm?

I'm stuck here :) would like to have some advice in where to search. Thanks so much for the advice.

[swansont]

I don't see how you got your answer for I; both the number and the units are wrong ([0.05m]^2*200kg = 0.5 kg m^2), but the equation for I is M(r^2 +R^2)/2 for a cylinder of finite thickness.  

Where is 2.618 rad/s2 coming from? What does "25 RPM - 1 sec" mean?

Rotating at a constant speed requires no net torque. The torque will tell you how quickly it will get up to speed