Calculating Required Force for 20 RPM Rotation on 4m Axel with 100kg Load

[kalpesh]

Hello,

This will be a very simple questions for all you pro's out there.
I want to know the amount of horsepowers required to start the rotation and maintain a rotation of 20 RPM of an axel which has an arm of 4 mts having a load of 100 kgs at the end of the arm.

the dia of tha axel is 1000mm (10 Cm.) and the leangth of the arm as stated above is 4 meters.

Please help

 

[ShawnD]

Technically the answer is 0.

The only thing reason the system will need power to keep it going is because of friction, a variable you don't know.
For a second I thought (mv^2)/r would have something to do with it but that force is exerted by the 4m bar and not a motor connected to a shaft.

If you give a required torque specification for that given RPM, I can tell you how much power you need.

btw, I voted no.

 

[rdt2]

The final speed isn't important - what you need to decide is the rate at which your device (which sounds more like a centrifuge than an axle) gets to that speed, i.e the (angular) acceleration. Once it's up to speed you just need to overcome friction losses, etc to keep it there.