Mechanical Energy: Where Does It Go?

[isyang94]

When a pendulum is let go from an elevated area, it will eventually stop swinging. But if this occurs then where had the mechanical energy gone to?

 

[Bill_K]

It's dissipated as heat, mostly from wind resistance, some from the flexing of whatever's holding it up.

 

[isyang94]

explain in details please

 

[isyang94]

because according to the law of conservation of energy, the gravitational potential energy and the kinetic energy would just stay the same the whole time but it is only slightly dissipated by heat, where else does it all go?

 

[S_Happens]

You were already given the correct answer.

It's not swinging in a vacuum. The energy is dissipated through friction with the air (drag) while it is in motion and through heat as whatever holds it up is flexed. Like you said, energy must be conserved and HAS to go somewhere. Since the pendulum only interacts with the surrounding environment, then that is where it has gone.

Don't put your own interpretation onto conservation of energy because you're taking an introductory physics class. Friction is a NON-CONSERVATIVE force, meaning that you cannot consider the motion of a pendulum in the real world to be path independent. The path that it travels causes drag, and a reduction of the energy within the pendulum.