Does Rotating an Object Absorb Energy?

[AliensRule77]

I took physics in school, but our class kind of skipped over rotational motion, so I was just reading about it myself. I was wondering about whether rotating an object absorbed some of the energy put into it and, if so, how to calculate how much is transferred to the rotation.

 

[chrisbaird]

Everything that happens in rotational motion is analogous to what can happen in linear motion. You can have conservation of angular momentum just like conservation of linear momentum. You can angularly accelerate an object by applying a force just like you can linearly accelerate an object. When you apply a force F to an object you do work on it and give it kinetic energy.

 

[AliensRule77]

Ok so then the angular momentum and linear momentum both work similarily but don't affect each other directly? Or am I wrong?

 

[Bipolarity]

Ok so then the angular momentum and linear momentum both work similarily but don't affect each other directly? Or am I wrong?

When objects move we use linear motion. When objects rotate about axes, we use angular motion.

Linear quantities are usally defined in terms of distance whereas angular quantities are usually defined in terms of angles, whose fundamental measure is the radian. The radian is a fundamental unit of angles just like the meter is for length. On a most fundamental level these two quantities have no relation to each other.

All the angular quantities therefore have their own equations of motion completely independent of the equations of the ones of linear motion.

Mass, Momentum, forces and energy is a different story.
The angular version of these quantities is heavily dependent on the linear version. In fact the angular version of these quantities is usually the sum of all the linear components of the various rotating particles. The rotational kinetic energy is the sum of the translational kinetic energy of each individual mass element involved in the rotation. Same thing for momentum, mass and force. Rotational work is the work done by the tangential force, not the centripetal force etc...

 

[AliensRule77]

Ok thank you, I think I understand it now.