What I have ? Have a 16’ x 72’ rotating drum There is a solid circular sector inside the drum What I need ? Want to Calculate the torque required to move that solid circular sector from the intial position to the position shown in attached picture (90 Degrees rotation) Data : RPM = 10 time = 15 seconds What I have caluted ? Calculated the torque required to rotate the drum using Torque = Moment of Inertia X Alpha where Alpha = angular acceleration How do I proceed ? Do I have to calculate the moment of inertia of that solid circular sector and then use the same formula? But here its not a complete rotation. Its just 90 degrees. So how to arrive at torque to move a mass about an axis only to a certain degree? Or, Should it be just Torque = Force * Radius ? where force shall be its mass * acceleration due to gravity and radius shall be distance from the drum's rotation axis to the circular sector's center of gravity ? Does Perpendicular axes theorem or Parallel Axes theorem come into the picture ?