OT: The 10th Demention

[se5a]

because you have to spend the same amount or more energy getting an object back up the hill as you got from it rolling down the hill.

[Raapys]

because you have to spend the same amount or more energy getting an object back up the hill as you got from it rolling down the hill.

But that's not actually true. If you pick up a box and hold it for one hour then you've spent alot more energy than if you merly lift it up and drop it at once. Yet, the box doesn't have any more energy when it falls after one hour than it does if you release it instantly. So where did the energy you continously applied to the box for one hour go?

PhoenixD: Alright, I can go with the spacetime theory as passable, but that still doesn't account for the fact that gravity does 'consume' the kinetic energy of masses, which means we still have a change in the amount of energy in the universe. Or am I missing something? Where's the kinetic energy going?

It does all sound a little odd, since if energy = mass, and mass is what creates gravity, and gravity drains energy, then we're left with mass that is actually consuming itself.

Oh, and while we're on the mystic and unexplained, does anyone know why *REPLICA WATCHES* are so popular? My inbox has been continously spammed with that stuff for over a year.

[Spoo]

Raapys said:
If you pick up a box and hold it for one hour then you've spent alot more energy than if you merly lift it up and drop it at once. Yet, the box doesn't have any more energy when it falls after one hour than it does if you release it instantly. So where did the energy you continously applied to the box for one hour go?

Your muscles require a constant use of energy to remain contracted. That energy ultimately "goes" into heating your body over the course of the hour that you spent holding the box.

[Raapys]

But you're keeping your muscles contracted *to keep the thing from falling to the ground*, thus you are, for that entire hour, applying more and more kinetic energy to the box. Put it like this: if the gravity was to suddenly vanish, the box would go flying off from the force you were exerting on it at that given moment. You're not exerting any less force on it just because it's not moving.

[Suicide Junkie]

It would drift off very slowly.

It starts at rest relative to you and the surface of the Earth, and you will be pushing 9.8m/s^2 for maybe 1/10th of a second before you notice and stop pushing.

You aren't actually adding any kinetic energy to the box.
Work = force * distance.

Effort feels more like force * time, but it dosen't have any serious meaning.

[Raapys]

But the 'work = force * distance' function is fatally flawed when used in this situation, because the result of the equation will be zero, indicating no energy has been spent, no work has been done. Obviously this is completely incorrect, since you'll be standing there sweaty and tired, having wasted alot of energy on the task.

I think a fitting metaphor would be two guys pulling each side of a rope. They're both applying kinetic energy to the rope, but in different directions, canceling it out. So even if the rope isn't actually moving, there's still alot of work being done on it. The difference is that where both these two guys would eventually get tired, gravity does not.

Hmm, I guess one solution would be that the force you're using to hold the box up is simply being applied as kinetic energy to the *Earth*, thus seemingly 'disappearing' since it's hardly noticeable for something on that scale.

[se5a]

they're not applying kinetic engergy, it would be... burning organic matter and turning it into heat mostly.
I think...

[Spoo]

Raapys said:
But the 'work = force * distance' function is fatally flawed when used in this situation, because the result of the equation will be zero, indicating no energy has been spent, no work has been done. Obviously this is completely incorrect, since you'll be standing there sweaty and tired, having wasted alot of energy on the task.

Work is being done in the sense that ions are being moved around in your muscle cells to keep the muscle contracted.

I think a fitting metaphor would be two guys pulling each side of a rope. They're both applying kinetic energy to the rope, but in different directions, canceling it out. So even if the rope isn't actually moving, there's still alot of work being done on it. The difference is that where both these two guys would eventually get tired, gravity does not.

The rope isn't moving, thus it has no kinetic energy. Likewise, no work is done on the rope (although the two guys will grow tired because work is being done within their muscle cells).