Questions about physics, especially gravity and electromagnetism

[Night Fox]

ok, first is like
for orbit, and every other kind of movement in space, where does all the energy come from? like, we're always moving through space, but the earth isn't putting out. I don't understand! no energy is required for orbit, besides what gets you there in the first place, right? so why do you keep moving? it seems like cheating. as soon as you're done accelerating, there's no issue of power. but why not?!

second: does mass affect the speed of acceleration in zero-gravity? like, a baseball and a car with the same engine, would there be any difference in the amount of energy required to get them to the same speed?

third: if you have a generator, and you're in zero-gravity, and you get it going, would it require less power to keep it going than it would on earth? since there's no gravity, there'd be a little less resistance, right?

fourth: speaking of generators... this one is a little hard to explain. but imagine a really large, circular tube surrounding the earth way up in orbit. the tube isn't (necessarily) turning, unless it would need to. but there's a big magnet moving in orbit, through the tube, and the inside of the tube is like, a really really long coil of wire (whatever kind of wire would allow for electromagnetic induction. like in generators). or the tube could be the magnet and the orbiting thing could be the wire coil, but I doubt that would be as effective. so, what I'm asking is, would that work to generate electricity? like, I'm sure it's not feasible right now, and it would be very expensive, I'm sure, but it is possible?

I probably seem stupid asking these questions. but I'm curious. and I can't ask my teacher, because he's not actually knowledgeable about it, he's just a baseball coach that the school got to teach a class because they didn't have enough teachers or couldn't afford to pay enough teachers idk

[Ad Bot]

[Thé Lord Tony]

Energy comes from the earth's core.

[Gojira]

1) the energy comes from gravity. the only reason astronauts free float is because they're basically in an eternal free fall. they're moving parallel to the earth's surface so fast that they literally miss the earth.
2) yes, the baseball would get to the required speed far faster because it has a higher thrust to weight ratio
3) possibly, it might actually run worse, because it's all just floating around in zero gee.
4) the tube would turn regardless, because it's orbiting, and a ring around the earth would be ridiculously impractical for power usage, because how much would it cost to make a ring around low earth orbit? trillions.

[Kearn]

ok, first is like
for orbit, and every other kind of movement in space, where does all the energy come from? like, we're always moving through space, but the earth isn't putting out. I don't understand! no energy is required for orbit, besides what gets you there in the first place, right? so why do you keep moving? it seems like cheating. as soon as you're done accelerating, there's no issue of power. but why not?!

second: does mass affect the speed of acceleration in zero-gravity? like, a baseball and a car with the same engine, would there be any difference in the amount of energy required to get them to the same speed?

third: if you have a generator, and you're in zero-gravity, and you get it going, would it require less power to keep it going than it would on earth? since there's no gravity, there'd be a little less resistance, right?

fourth: speaking of generators... this one is a little hard to explain. but imagine a really large, circular tube surrounding the earth way up in orbit. the tube isn't (necessarily) turning, unless it would need to. but there's a big magnet moving in orbit, through the tube, and the inside of the tube is like, a really really long coil of wire (whatever kind of wire would allow for electromagnetic induction. like in generators). or the tube could be the magnet and the orbiting thing could be the wire coil, but I doubt that would be as effective. so, what I'm asking is, would that work to generate electricity? like, I'm sure it's not feasible right now, and it would be very expensive, I'm sure, but it is possible?

I probably seem stupid asking these questions. but I'm curious. and I can't ask my teacher, because he's not actually knowledgeable about it, he's just a baseball coach that the school got to teach a class because they didn't have enough teachers or couldn't afford to pay enough teachers idk

1. no momentum is constant because there's no friction

2. obviously

3. generators wouldn't even work in space because the fuel would float in the fuel tank instead of flowing correctly

4. no because you need to have contact and that would produce friction which would cause it to stop not to mention the insane amounts of energy you'd need to not only get it to move but to keep it from smashing into its containment unit

[Gojira]

1. no momentum is constant because there's no friction

2. obviously

3. generators wouldn't even work in space because the fuel would float in the fuel tank instead of flowing correctly

4. no because you need to have contact and that would produce friction which would cause it to stop not to mention the insane amounts of energy you'd need to not only get it to move but to keep it from smashing into its containment unit

there's also the fact of how much money it would cost to get the damn generator to orbit in the first place that makes it not worth it

and what kearn said for 3 is effectively what i was trying to say

[Swat 3]

Energy comes from the earth's core.

Of course, but this doesn't answer the question. When you are in Deep space, does the energy comes from the Earth? No. Gravity can move things by force.

When satellites orbit, they go fast enough, yet they are falling.

This keeps them in the same position(from the ground, you move around the Earth still) because Earth is round.
No energy is required for orbit yes, but you get there by going against gravity with rockets, then burn to get in orbit. Gravity keeps the ship going at it's same speed because of no friction in space (no momentum.)

3rd: You wouldn't be able to get the Generator working in the first place. What do you mean less power to keep it going? You mean fuel?

4th: I wouldn't think this would work.. no.

[Gojira]

Of course, but this doesn't answer the question. When you are in Deep space, does the energy comes from the Earth? No. Gravity can move things by force.

When satellites orbit, they go fast enough, yet they are falling.

This keeps them in the same position(from the ground, you move around the Earth still) because Earth is round.
No energy is required for orbit yes, but you get there by going against gravity with rockets, then burn to get in orbit. Gravity keeps the ship going at it's same speed because of no friction in space (no momentum.)


3rd: You wouldn't be able to get the Generator working in the first place. What do you mean less power to keep it going? You mean fuel?

4th: I wouldn't think this would work.. no.

read my post

[Swat 3]

read my post

I was typing this for a while right after he posted..

:C

[Night Fox]

Energy comes from the earth's core.

seriously

1) the energy comes from gravity. the only reason astronauts free float is because they're basically in an eternal free fall. they're moving parallel to the earth's surface so fast that they literally miss the earth.
4) the tube would turn regardless, because it's orbiting, and a ring around the earth would be ridiculously impractical for power usage, because how much would it cost to make a ring around low earth orbit? trillions.

1. yeah. but where does that come from? just existing gives something energy? that doesn't make sense
4. I don't think the tube would have needed to spin, and I worded it pretty bad when I said "in orbit," because I really just meant up there somewhere. but impracticality and cost is irrelevant because I said it was

2. obviously
3. generators wouldn't even work in space because the fuel would float in the fuel tank instead of flowing correctly
4. no because you need to have contact and that would produce friction which would cause it to stop not to mention the insane amounts of energy you'd need to not only get it to move but to keep it from smashing into its containment unit

2. I don't see how. there's no friction in space, no weight, or anything, so I don't understand why it would make any difference whether something weighs one pound or one ton
3. let's assume you found a way to deal with that
4. I see. my textbook never mentioned that it required contact. don't think it would take a lot of energy to get it moving or to keep it from hitting the edges of the tube, though. not much more than it takes to get into orbit with any other spacecraft

alright since I didn't make it clear that I don't mean just orbit with the first question, let's replace that with "where does gravity get energy from"

[Gojira]

1. yeah. but where does that come from? just existing gives something energy? that doesn't make sense
4. I don't think the tube would have needed to spin, and I worded it pretty bad when I said "in orbit," because I really just meant up there somewhere. but impracticality and cost is irrelevant because I said it was
2. I don't see how. there's no friction in space, no weight, or anything, so I don't understand why it would make any difference whether something weighs one pound or one ton
3. let's assume you found a way to deal with that
4. I see. my textbook never mentioned that it required contact. don't think it would take a lot of energy to get it moving or to keep it from hitting the edges of the tube, though. not much more than it takes to get into orbit with any other spacecraft

alright since I didn't make it clear that I don't mean just orbit with the first question, let's replace that with "where does gravity get energy from"

not even top physicists know what exactly causes gravity.
it's possibly from a theoretical particle known as the graviton
theoretical meaning it's unconfirmed, not experimentally tested, etc.
and then there's the higgs boson which supposedly gives stuff mass, but we haven't proven that exists either

[Kearn]

2. I don't see how. there's no friction in space, no weight, or anything, so I don't understand why it would make any difference whether something weighs one pound or one ton
3. let's assume you found a way to deal with that
4. I see. my textbook never mentioned that it required contact. don't think it would take a lot of energy to get it moving or to keep it from hitting the edges of the tube, though. not much more than it takes to get into orbit with any other spacecraft

1 why are you even talking about weight it's a 0g environment

2. except you wouldn't because whatever you were using would affect the rest of the generator and put you back where you started

3. you can't make a near-perpetual motion machine and expect to be able to take energy from it without it losing momentum

also you have to keep it basically perfectly in place so it doesn't break the contact brushes or lose contact which is basically impossible when you're using something 15000 miles across

[Zeblote]

Since this is a physics thread this is perfect
Can someone explain to me how this works
http://www.youtube.com/watch?feature=player_detailpage&v=oJv58SXx2V8#t=159s

[Kearn]

Since this is a physics thread this is perfect
Can someone explain to me how this works
http://www.youtube.com/watch?feature=player_detailpage&v=oJv58SXx2V8#t=159s

magnets

obviously not a perpetual motion machine, actually would act as a very weak mechanical generator

[Swat 3]

When something gets so massive, it creates gravity.

Gravity pulls things to it.
This is force.

Force requires energy.

This energy probably comes from the molecules in you (or a thing) or that are surrounding you (or a thing.)

[Night Fox]

1 why are you even talking about weight it's a 0g environment
2. except you wouldn't because whatever you were using would affect the rest of the generator and put you back where you started

1. instead of complaining about what words I used or whatever you're doing, answer the question
2. first of all, an electric pump wouldn't even use all the energy that a gas generator creates. that's ridiculous. and besides that, you could always do it the old way, and use a manual pump