Ask a physicist anything. (2)

[Cabal]

I'm sure that's why it's prefaced by, "micro-".

Technically, "micro" would imply scales of the order of 10^-6, which isn't nearly comparable to the situations we're talking about, so no.

For the sake of attenuation though, I'll consider both of our points valid ones.

How's that?

Which point of yours, exactly?

 

[Cabal]

Hence why I said "to a good degree of accuracy" .

Woopsie, yes you did! But you know you're going to get argued with now though!

And besides, the true system is a very good approximation of the idealised case.

Quite!

 

[Cabal]

"Zero gravity" is a term that is one vote away from being plutoed ---

If you want to call it ".000000000000000000000000000000000000000001gravity", be my guest.

 

[AV1611VET]

If you want to call it ".000000000000000000000000000000000000000001gravity", be my guest.

Micro-gravity will do just fine, thank you.

 

[Sanguis]

Hmmm, just thinking about it, hypothetically if a mass is perfectly central to all the other mass in the universe, so there's equal force pulling on it from all directions, would that then be zero gravity?

 

[Wiccan_Child]

"Zero gravity" is a term that is one vote away from being plutoed ---

Ah, Pluto. I like to think of it as an honorary planet, if only to spare its feelings .

 

[catzrfluffy]

Thank for all your answers

I sort of meant does the Moon always go round in the same angle of orbit, and is this affected by the turn of the Earth on its axis at all?

I thought G-force was caused by all the air molecules hitting you, and pinning you to the chair in a roller coaster, thus the vacuum question?

 

[Wiccan_Child]

Hmmm, just thinking about it, hypothetically if a mass is perfectly central to all the other mass in the universe, so there's equal force pulling on it from all directions, would that then be zero gravity?

Yes, assuming gravitational pressure had equalised (i.e., there are no gravity waves still propagating through space; otherwise, the mass would experience a net pull).

 

[AV1611VET]

Ah, Pluto. I like to think of it as an honorary planet, if only to spare its feelings .

Same here --- as does California, Illinois, and New Mexico.

"Pluto", as a verb, is the 2006 Word of the Year, by the American Dialect Society.

http://www.cnn.com/2007/US/01/07/word.of.the.year/index.html

 

[Wiccan_Child]

Thank for all your answers

I sort of meant does the Moon always go round in the same angle of orbit, and is this affected by the turn of the Earth on its axis at all?

Not entirely. The Moon was formed when a large, Mars-sized planet hit the Earth. A lot of the Earth's surface was thrown into space, and this became the Moon (that's why the Moon's entire composition resembles the Earth's crust). So the exact orbit depends on the Earth's previous axis of rotation, the angle with which is was hit, etc.

I thought G-force was caused by all the air molecules hitting you, and pinning you to the chair in a roller coaster, thus the vacuum question?

Ah, I can see where you're coming from, but it's actually the other way around: it's the chair accelerating into you, since it's the chair that physically moves you forward.

Think about being in a car. When the car accelerates, you feel g-forces pushing you into the seat, right? But there's no wind, so it can't be the air molecules. Rather, it's the entire car that's moving forward faster than your body is, so you feel it pushing into you. From your point of view, however, it's as if you're being pulled backward.

 

[catzrfluffy]

If something was accelarating just on it's own, would it feel G-force?

What if someone went really fast on roller skates, would they feel G-force?

 

[Cabal]

If something was accelarating just on it's own, would it feel G-force?

What if someone went really fast on roller skates, would they feel G-force?

Yup and yup.

 

[Wiccan_Child]

If something was accelarating just on it's own, would it feel G-force?

Yep. A car rolling freely down a hill would experience g-force on its axles.

What if someone went really fast on roller skates, would they feel G-force?

Yes, they'd feel it on their heels.

 

[Cabal]

Hmmm, just thinking about it, hypothetically if a mass is perfectly central to all the other mass in the universe, so there's equal force pulling on it from all directions, would that then be zero gravity?

"Central" wouldn't be the word I'd use, but in theory one should be able to find a Lagrange point for the entire universe, so to speak. Given how in motion everything in the universe is, it wouldn't last though, plus defining coordinates would be a nightmare....

 

[Cabal]

Yep. A car rolling freely down a hill would experience g-force on its axles.


Yes, they'd feel it on their heels.

Why specifically only those points? The entire object is accelerating.

 

[Chesterton]

The reason I was asking about the electrons in heated metal is this: when I think of something producing energy I think of something permanently changing it's material state, i.e., fusion in a star, or wood burning in a fire. But the electrons in metal will simply change their state, and then change back again? Nothing is "given up" to produce the light energy?

 

[Wiccan_Child]

Why specifically only those points? The entire object is accelerating.

The wheels would be experiencing friction, so would accelerate slower than the rest of the car. This means the chasse is pressing on the axle, thus creating g-force.

 

[Wiccan_Child]

The reason I was asking about the electrons in heated metal is this: when I think of something producing energy I think of something permanently changing it's material state, i.e., fusion in a star, or wood burning in a fire. But the electrons in metal will simply change their state, and then change back again? Nothing is "given up" to produce the light energy?

Nope. The energy to produce light comes from the energy that heated it up in the first place. Kinetic energy from the motion of electrons flowing round a circuit goes to potential energy when they collide with electrons in an atom, exciting them. This energy is then released in the form of a photon when the electron de-excites back into its original state.

 

[Cabal]

The reason I was asking about the electrons in heated metal is this: when I think of something producing energy I think of something permanently changing it's material state, i.e., fusion in a star, or wood burning in a fire. But the electrons in metal will simply change their state, and then change back again? Nothing is "given up" to produce the light energy?

Well, changes of state usually implies some kind of reaction - the best example to look at is the wood burning one - in that case, electrons are actually transferring from atom to atom as the wood reacts with oxygen into ash.* Merely heating metal, on the other hand, isn't enough to help the atoms escape their associated atoms the way they are in burning wood.


*Incidentally, the glow of something burning IS due to atoms of that material having their electrons giving off photons, however, so it's really a blend of processes.

 

[Cabal]

The wheels would be experiencing friction, so would accelerate slower than the rest of the car. This means the chasse is pressing on the axle, thus creating g-force.

I was under the impression g-force was just acceleration scaled against g ("force" is a misnomer).

You're right, there would be a force felt due to the difference in applied forces, but that's not g-force. Additionally, something not experience this difference in forces will still feel an applied acceleration.