Torque needed to spin a marble slab at π rad/s with friction losses

[mawais15]

Calculating Torque??

i wonder how would i calculate the amount of torque required to give a rectangular piece of marble, an angular velocity of pi radians/second given the angular moment of inertia of that slab.

The bearing supports holds a coefficient of friction of 0.2 and the shaft diameter is 20mm. the angular moment of inertia of the slab about the rotation axis is 200 kg-m2. The distance between supports is 1 meter and the slab is in the center of the shaft.

Regards

 

[tiny-tim]

hi mawais15!

i wonder how would i calculate the amount of torque required to give a rectangular piece of marble, an angular velocity of pi radians/second given the angular moment of inertia of that slab.

torque gives you angular acceleration (τ = Iα), not angular velocity …

once you find the angular acceleration, you can get the angular velocity using the standard constant acceleration equations

 

[mawais15]

hi mawais15!


torque gives you angular acceleration (τ = Iα), not angular velocity …

once you find the angular acceleration, you can get the angular velocity using the standard constant acceleration equations

how about incorporating the bearing friction to maintain the desired angular velocity?

 

[tiny-tim]

the friction with the bearings is a torque also, so you just subtract it from the applied torque

 

[mawais15]

but i the question is that how much torque do i have to apply..