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I am building a spit to roast a pig. Instead of just getting a motor recommended to be powerful enough I would like to understand the math required to spec it out. I have no experience with physics but I have been reading about force, torque, and power.

Most of what I have read about torque relates to the product of force exerted on a lever attached to an axis or fulcrum at a particular speed. But what if there is no lever?

I want to know how much force is necessary to rotate a 100 lb pig. I understand there will be gravitational forces and frictional forces mitigating the inertia of the pig. Furthermore, I will be using gears to reduce the 1,000 rpm speed of the motor to 3-4 rpm for the spit.

An explanation of the necessary math for this problem would be much appreciated.

thanks,

gary

2. Relevant equations

3. The attempt at a solution

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# Force calculation help

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