Recent content by dozer811

I didn't think the air drag would make that much of a difference, but it does get pretty windy in there when its running. Also I meant to say that the application point of the force is not changing.

This is a rough sketch of the situation. Note that I am concerned with steady state and that the masses are roughly equal.

I understand that a larger torque must be applied to speed up the rotation, but once the system is running at a steady speed (ie no angular acceleration), then the only torque applied is to overcome friction. The two setups should have the same friction because the mass differences are neglible...

We took a centrifuge that rotated a large metal disk (~15" radius) that could rotate up to 600RPM. The disk was removed and replaced with a beam (~30" radius) which holds a mold at each end. The total mass of the beam and two molds is about the same as the disk. However, the beam/mold...

If friction is the cause of the torque at constant speed, then why can a disk rotate much faster than two objects of the same total mass rotating at a greater distance?

Thats what I thought. The reason I am asking is because we can rotate the centrifuge at 600RPM with no load, but only about 250 RPM before the motor starts to overheat (it's big). Is the extra torque produced with an added load due only to the increase in friction?

I am trying to determine the torque exerted by a motor running a centrifuge at constant speed. How do you determine torque when there is no acceleration? I know it's there somewhere...