OT: The 10th Demention

[Raapys]

The ripping process eats up a lot of energy in the breaking of bonds and a bit in the final acceleration of the two halves of the rope.

In other words, work is being done on the rope, even though the work formula wont agree. The kinetic energy being applied by the two guys pulling the rope are ripping apart the bonds holding it together. Right?

The thing you're not getting is that you don't "apply kinetic energy" to anything. You exert forces. The force may be countered by friction or an opposing force.

But that was my point; if you're fighting gravity, or magnetism, then isn't energy "disappearing", since gravity and magnetism doesn't weaken( i.e. they have infinite power )?

And also, why wouldn't 'exerting forces' be exactly the same as applying kinetic energy? It's no less 'applying k. energy' just because it's not moving; that just means another force is applying a bigger amount of kinetic energy than you are, and in a different direction. Or in the case of an atmosphere, where you're not just pushing the object, but the air particles covering the direction you're pushing it in as well.

[AgentZero]

Raapys said:
And also, why wouldn't 'exerting forces' be exactly the same as applying kinetic energy? It's no less 'applying k. energy' just because it's not moving; that just means another force is applying a bigger amount of kinetic energy than you are, and in a different direction. Or in the case of an atmosphere, where you're not just pushing the object, but the air particles covering the direction you're pushing it in as well.

Kinetic energy is loosely defined as "extra energy an object has due to motion." You cannot apply kinetic energy to anything. You just can't. What you can do is apply force to an object, and if the force you apply to the object makes it move, then it gains kinetic energy, but you didn't give the object the kinetic energy. You gave the object force, which resulted in motion, and by virtue of said motion, it gained kinetic energy.

As for objects not moving, keep in mind that the law of conservation of energy states that you cannot create or destroy energy, only convert it between forms. So, you go and push on a big rock. You're using chemical energy derived from food to apply force to the rock. But say it's a big rock, and it won't move. The chemical energy you use to create the force is thus converted into heat in your body. Have you ever noticed you get hot & sweaty faster when you try to move something that's too heavy to move, compared to something that's just heavy enough that you can move it? I'll probably get whacked by the sciency folks for that comparisson, but my grade 11 physics teacher used it to illustrate the point, so I'm using it too.

I hope that made sense.