OT: The 10th Demention

[GuyOfDoom]

Darwin's theory was *wrong*

Admittedly I've never read Origin of Species, but I don't believe he states where life started, which is a large misconception. As for his theory being wrong, I'm confused as Evolution happens, but not precisely in the way he was able to observe at the time.

[narf poit chez BOOM]

I could explain how standing on a surface does not use energy save in inneficiency, but Fyron was the one who explained it to me and as it's been about a year, I'm not sure I can explain it.

[Renegade 13]

And the force you are applying to the aforementioned large rock isn't disappearing either; it's being "eaten up" by friction between the rock and the Earth, etc. You could apply a lot of force to the rock, but if you can't overcome the coefficient of friction, all you're doing is ultimately applying all the energy you exerted on the rock into the Earth, which is holding the rock still.

[Raapys]

Yeah, but then 'what is force'? Isn't exerting force actually just transference of kinetic energy? If an object floats, completely still, in space, and another object bumps into it, isn't it true that the previously still object will start to move and the previously moving object will stop( assuming a perfect collision between like masses )?

Renegade, friction wont matter if you're lifting it straight upwards, though.

Anyway, I'll try not to drag this around in circles forever. I was just thinking that surely gravity would be both a creator and a destructor of energy.

Given a rope, a tree, a bucket of water, a gravity switch and Earth: The tree is on earth, the rope is hanging from the tree, the bucket of water is hanging from the rope and is so heavy that it'll snap the rope within one minute. The gravity switch is off.

You turn on the switch. What happens? Gravity starts pulling, exerting force as you would say, on everything. With the help of the bucket of water, gravity is actually pulling with enough energy to break the bonds in the rope.

The big question: Where's gravity getting its energy from? And even if gravity itself doesn't actually need any energy to work( i.e. spacetime ), gravity *is* exerting force on the bucket making it move. When it's moving it has kinetic energy. Since gravity made it move, that means gravity *created* energy, no?. To our knowledge, gravity doesn't weaken over time( unless given external events ). Gravity could be doing this with billions and billions of buckets all over the world, forever really. So what am I missing? How is this not an infinite energy scenario and something that breaks the law of conservation of energy?

Sorry if I'm being difficult. I understand what you guys are saying; it's along the lines of what I did learn when I actually went to school. I just can't get it all to add up.

And how is it that a photon can slow down when passing through other mass, then speed up again on its own accord? Doesn't that too go against a number of laws?

[Suicide Junkie]

You don't have to expend energy to apply a force. The spring in your ballpoint pen (the clicky kind) is always exerting force on the clicker, but that dosen't in itself mean that the pen is mightier than the sword.

Change in energy = Work = Force (dot) Distance
(Dot product of the vectors) this is the same as simple multiplication if the force and movement are in the same direction. (Negative if they're in opposite directions, and zero if they are perpendicular)

No movement means no transfer of kinetic energy regardless of the force applied.

[AngleWyrm]

Something's amiss with the Work formula. If I lift a brick straight up it takes some effort. If I lower that brick straight down, it doesn't feel like I've exerted as much effert. If I push it sideways on a slippery surface, it takes almost no effort at all.

If I carry a rock to the top of a mountain, did I store energy in some sort of battery? Potential Energy? I notice that pendulums and bouncy balls and roller coasters have enough energy in their battery to bounce all the way back up to very nearly where they were. Odd that we say it was Momentum carried it back up to where it was. If I put enough energy in a brick to lift it six feet from the sand, we have no problem saying that was just enough energy to go back down. But it looks like twice as much on the way down, doesn't it?

What if I tossed a steel marble up in a vacuum sealed metal box here on earth? Would it continue to bounce up to some specific height? And doesn't that look a lot like orbiting, viewed from an angle?

[AgentZero]

Something's amiss with the Work formula. If I lift a brick straight up it takes some effort. If I lower that brick straight down, it doesn't feel like I've exerted as much effert. If I push it sideways on a slippery surface, it takes almost no effort at all.

I only got a C in highschool physics, so I'm no expert, but the way I remember it working is this: When you lift the brick, you're working against gravity, so you personally do most of the work, so it seems hard. When you lower the brick, gravity is doing most of the work, so to you it seems easy. But either way, the same amount of work is being exerted on the brick. I think the work formula by itself is based on moving things through the air, and you have to make additional calculations for friction when you're moving an object across a surface. Or something. I was sick when we covered friction so I'm kinda fuzzy on it.

What if I tossed a steel marble up in a vacuum sealed metal box here on earth? Would it continue to bounce up to some specific height?

Things stop bouncing because every time they hit the object they're bouncing against, they transfer some of their energy into what ever they're bouncing against, so your marble would probably bounce just the same in a vacuum as it does in the atmosphere, since air friction plays a very small part in slowing the marble. Otherwise, air being thin as it is, things would bounce for a very long time!

[Phoenix-D]

GuyOfDoom said:

Admittedly I've never read Origin of Species, but I don't believe he states where life started, which is a large misconception. As for his theory being wrong, I'm confused as Evolution happens, but not precisely in the way he was able to observe at the time.

No, I don't think he did. However the view of evolution posited in that book has gone through so many revisions I feel quite comfortable in saying he was wrong.

[Suicide Junkie]

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 the ship example, presuming the block and shots all stick together, you end up with a block with two bullets in it, and two ships both moving away from the block.

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.
You can waste energy all you want, you'll just get hot and sweaty without getting the result you wanted.

[se5a]

we don't need to "invent" a kenetic energy weapon, we've already got them, that is precicely what a rifle is.
an object has kenetic energy when it is moving.
when it is at rest, it has no kenetic energy.