Torque required to rotate a circular sector inside a drum

In summary, the conversation discusses the calculation of torque required to move a solid circular sector inside a rotating drum from its initial position to a 90 degree rotation. The data provided includes the drum's RPM, time, and the need for calculating the moment of inertia using the parallel axis theorem. The definition of angular acceleration is also mentioned. The approach suggested is to find the inertia of both separately and calculate their individual torques. The conversation ends with the calculation of angular velocity and acceleration.
  • #1
subbby
22
0
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 ?
  1. Do I have to calculate the moment of inertia of that solid circular sector and then use the same formula?
  2. 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?
  3. 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 ?
  4. Does Perpendicular axes theorem or Parallel Axes theorem come into the picture ?
 

Attachments

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  • #2
You will need to get the total moment of inertia of the drum + circular section. For that you may need the parallel axis theorem.

As for the rotation of the 90 degrees. What is the definition of angular acceleration?
 
  • #3
rock.freak667 said:
You will need to get the total moment of inertia of the drum + circular section. For that you may need the parallel axis theorem.

As for the rotation of the 90 degrees. What is the definition of angular acceleration?

I am afraid , I didn't understand. My approach was to find the Inertia of both separately and then arrive at their individual torques. Did you mean the same ? Do we need a parallel axis theorem in that ? If yes, could you explain a little more elaborately ?

Angle was taken to be ∏/2.
Therefore, Angular Velocity = (∏/2)*rpm/60 = (∏/2)*10/60=.26 s^(-1)
and Angular acceleration = .26/time = .26/15 =0.0174 s^(-2)

Thanks for your help !
 

1. What is torque?

Torque is a measure of the force that causes an object to rotate around an axis. It is typically measured in units of newton-meters (N*m) or foot-pounds (ft-lb).

2. How is torque calculated?

Torque is calculated by multiplying the force applied to an object by the distance from the axis of rotation to the point where the force is applied. The formula for torque is T = F x r, where T is torque, F is force, and r is the distance from the axis of rotation.

3. What factors affect the torque required to rotate a circular sector inside a drum?

The torque required to rotate a circular sector inside a drum is affected by several factors, including the size and weight of the sector, the type of material the sector is made of, the friction between the sector and the drum, and the speed at which the sector is rotating.

4. How is the torque required to rotate a circular sector inside a drum determined?

The torque required to rotate a circular sector inside a drum can be determined by using the formula T = F x r, where T is torque, F is the frictional force between the sector and the drum, and r is the distance from the axis of rotation to the point where the force is applied. This value can also be measured experimentally using a torque sensor.

5. How can the torque required to rotate a circular sector inside a drum be reduced?

The torque required to rotate a circular sector inside a drum can be reduced by decreasing the size and weight of the sector, using materials with lower friction coefficients, and by rotating the sector at a slower speed. Lubrication between the sector and the drum can also help reduce the required torque.

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