Nobody ever teaches me how physics works

The other day I defined 'wind' to my brother as 'a change in air pressure in large scales', and it got me thinking that either I don't pay attention in school or school did not teach me the most simple things.

Here an example I can't explain:

When you have a collision where the momentum are opposing, the collision magnitude is additive.

For example 20 N·s -> <- 10 N·s = 30 N·s of momentum, assuming there's no loss of energy elsewhere.

In the example 20 N·s-> 10 N·s -> , the object behind the object in the front strikes the object in the front, but with momentum 10 N·s
Why does this happen? It's not sufficient to say that it is intuitive, and I was never taught why things happen. I was simply taught to apply trigonometry and algebra and solve for the equation.

Are there any questions about reality you have questions about? For example the reason I don't fall through the earth is because of electrostatic repulsion, or something like that (this explains why solid things do not pass through each other). WTF

PS what am I asking? is there a term for it?

it works because of Jesus

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Originally Posted by kotora

it works because of Jesus

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A wizard did it

No, Jesus.
Or are you saying Jesus is a wizard?

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Originally Posted by Mirage

No, Jesus.
Or are you saying Jesus is a wizard?

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Jesus is God wizard. He casts zapzap at Satan and makes him dead.

I was in the process of composing a serious response until I realised pg made this thread

My question is serious but you guys love to be pgish in a pg thread.

And whose fault is that? :zombert:

In seriousness, because of what Newton figured out. So, it happens because the universe's physical laws demand it happen. If you mean why are those laws set up like that, that's way above my pay grade, the best we can do is "they just are".

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Originally Posted by I'm my own MILF

And whose fault is that? :zombert:

In seriousness, because of what Newton figured out. So, it happens because the universe's physical laws demand it happen. If you mean why are those laws set up like that, that's way above my pay grade, the best we can do is "they just are".

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Basically you don't know why conservation of energy happens :aimmad:

PG I love you but nomore thinking threads plz thx.

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Originally Posted by Bert

PG I love you but nomore thinking threads plz thx.

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LOL I'M ASIAN MOG SO ORGINAL LOLOLOLOL AMIBESTPOSTAR YET?

OMG I SAID ASL LOL WITTY

I just don't want to think about things like why :bou::bou::bou::bou: falls or why luquid stays in and object going in an orbit!

chosen reference frame conservation of momentum etc.

http://upload.wikimedia.org/wikipedi...sto%C3%9F2.gif

Does it have something to do with inertia? Being that the force of inertia on the object with N -> 20 has more inertia that overpowers the N->10 ? I think you're asking why the opposing force ends up being transferred between the objects. I think it has something to do with inertia.

Physics fail. ASL?

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Originally Posted by Dignified Pauper

Does it have something to do with inertia? Being that the force of inertia on the object with N -> 20 has more inertia that overpowers the N->10 ? I think you're asking why the opposing force ends up being transferred between the objects. I think it has something to do with inertia.

Physics fail. ASL?

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Yes physics fail. I want to know why if I push against an object the force doesn't push back at me, or gets transferred to a power plant in brasil. "because that's how it works" ?

All I know is that in high school, when it was time for my weekly beating, the bigger kids would all start pushing me over and laying into me while yelling "Physics lesson! Physics lesson!!"

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Originally Posted by Peegee

In the example 20 N·s-> 10 N·s -> , the object behind the object in the front strikes the object in the front, but with momentum 10 N·s
Why does this happen?

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Objects traveling at a constant speed are in force equilibrium. Thus if there is no resisting force (air friction, tire friction, etc), there is no force on the particle, and even if there was the forces working in opposite directions, assuming they are equal would still create zero resulting force (definition of constant speed). So if you are looking at a collision between those two particles, it is no different if they are 20 / 10 or 10 / 0 N.s

The first part i can't explain any different that a simple force balance with non-deforming particles.

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Originally Posted by Peegee

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Originally Posted by Dignified Pauper

Does it have something to do with inertia? Being that the force of inertia on the object with N -> 20 has more inertia that overpowers the N->10 ? I think you're asking why the opposing force ends up being transferred between the objects. I think it has something to do with inertia.

Physics fail. ASL?

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Yes physics fail. I want to know why if I push against an object the force doesn't push back at me, or gets transferred to a power plant in brasil. "because that's how it works" ?

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It doesn't exactly push back at you. If you push against a cabinet for example, and it doesn't give (no movement), the force pulling back at you, is here then the gravity working on the cabinet and the friction between the bottom of the cabinet and the floor. The reason it "pushes back at you" is because that friction force transfers through the material stiffness to your contact plane. If it was deformable, the force would in fact result in material deformation, instead of "pushing back".

Sorry if my explanation isn't really.. yeah. It's hard to explain things.

It makes sense. I do have eyes and a brain. I just don't understand how energy is transferred (and I don't think people really understand that either?)

You mean the transfer of inertial energy? It is a variation of kinetic energy. But to visualize that sort of energy transfer is impossible, because it is something we defined. It doesn't have a form as such, and can only be imagined in the form we defined it in, as we do with all transfer of energy (except perhaps electrical), if that makes sense.

Anywho, the way I think about energy transfer is with forces. One particle hits another, the particle will experience a force at the contact surface, with up to three vector directions depending on the axial system and how you define it. That force contributes to a change in velocity, etc.

I need to talk to physicists and I think Rubah would hate me if I asked her that question.

I was going to troll this thread by saying that it's impossible to see collisions because we're too busy measuring particle velocity :p but instead I guess the tiny bit of information I gathered is payment to maintain my good behaviour

:(

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Originally Posted by Peegee

I need to talk to physicists

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So...me?

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and I think Rubah would hate me if I asked her that question.

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Rubah is a Mechanical Engineer.

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Originally Posted by Aerith's Knight

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Originally Posted by Peegee

I need to talk to physicists

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So...me?

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and I think Rubah would hate me if I asked her that question.

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Rubah is a Mechanical Engineer.

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I don't know anything about you

And Rubah knows physics - she's a ME :coolface:

Rubah is azn?

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Originally Posted by NorthernChaosGod

Rubah is azn?

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Ask her. But I think so

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Originally Posted by Peegee

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Originally Posted by Dignified Pauper

Does it have something to do with inertia? Being that the force of inertia on the object with N -> 20 has more inertia that overpowers the N->10 ? I think you're asking why the opposing force ends up being transferred between the objects. I think it has something to do with inertia.

Physics fail. ASL?

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Yes physics fail. I want to know why if I push against an object the force doesn't push back at me, or gets transferred to a power plant in brasil. "because that's how it works" ?

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Its all about momentum which is a product of velocity and mass. If you and a 300lb guy are running at each other and collide, then your going back the other direction - whats so hard to understand :)

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Originally Posted by Juliebrenna

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Originally Posted by Peegee

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Originally Posted by Dignified Pauper

Does it have something to do with inertia? Being that the force of inertia on the object with N -> 20 has more inertia that overpowers the N->10 ? I think you're asking why the opposing force ends up being transferred between the objects. I think it has something to do with inertia.

Physics fail. ASL?

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Yes physics fail. I want to know why if I push against an object the force doesn't push back at me, or gets transferred to a power plant in brasil. "because that's how it works" ?

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Its all about momentum which is a product of velocity and mass. If you and a 300lb guy are running at each other and collide, then your going back the other direction - whats so hard to understand :)

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I want to know how energy is transferred and why it goes the direction it does.

I could explain with formulas but I dont think thats what your after. Energy can neither be created nor destroyed, only transfered. This is considerably more complicated than just change of motion. On any energy transfer there is transfer of heat for example - but its not something somebody thinks about. I am not really sure how to explain it without mathematics. Consider throwing a baseball - your merely transferring energy to the ball giving it an acceleration and velocity while some energy is lost in the act of throwing due to friction as it is released from the hand etc - thus creating heat loss and inefficiency. No energy transfer is 100% efficient.

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Originally Posted by Juliebrenna

I could explain with formulas but I dont think thats what your after. Energy can neither be created nor destroyed, only transfered. This is considerably more complicated than just change of motion. On any energy transfer there is transfer of heat for example - but its not something somebody thinks about. I am not really sure how to explain it without mathematics. Consider throwing a baseball - your merely transferring energy to the ball giving it an acceleration and velocity while some energy is lost in the act of throwing due to friction as it is released from the hand etc - thus creating heat loss and inefficiency. No energy transfer is 100% efficient.

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Here I'll use some layterms which will infuriate you more:

In a closed system energy is neither added nor removed. So if a closed system had say, 5000 KJ of energy, you should be able to itemize 5000 KJ of energy no matter how energy is moved around.

I'm asking why if I throw a ball, I lose 50 J of energy which goes to the ball. Why doesn't the 50 J go into Neptune? Why doesn't it go to the other side of the Eagle Nebula? The short answer is because those systems aren't part of the baseball and me system. It still doesn't explain how energy goes from me to the ball .

Well 50J may go to Neptune......lol ultimately because heat is transferred off the ball from friction and is released into the atmosphere. Some of earths heat is then lost into space - and ultimately minute amounts may make it all the way to Neptune :p. As far as your last question - newtons 2nd law.

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Originally Posted by Juliebrenna

Well 50J may go to Neptune......lol ultimately because heat is transferred off the ball from friction and is released into the atmosphere. Some of earths heat is then lost into space - and ultimately minute amounts may make it all the way to Neptune :p. As far as your last question - newtons 2nd law.

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Does the second law explain why entropy only goes one way and not the other? Like why it's impossible for something colder to give energy to something hotter without work.

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Originally Posted by Peegee

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Originally Posted by Juliebrenna

Well 50J may go to Neptune......lol ultimately because heat is transferred off the ball from friction and is released into the atmosphere. Some of earths heat is then lost into space - and ultimately minute amounts may make it all the way to Neptune :p. As far as your last question - newtons 2nd law.

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Does the second law explain why entropy only goes one way and not the other? Like why it's impossible for something colder to give energy to something hotter without work.

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Stop being Azn.

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Originally Posted by NorthernChaosGod

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Originally Posted by Peegee

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Originally Posted by Juliebrenna

Well 50J may go to Neptune......lol ultimately because heat is transferred off the ball from friction and is released into the atmosphere. Some of earths heat is then lost into space - and ultimately minute amounts may make it all the way to Neptune :p. As far as your last question - newtons 2nd law.

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Does the second law explain why entropy only goes one way and not the other? Like why it's impossible for something colder to give energy to something hotter without work.

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Stop being Azn.

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This thread got to involved. instead
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Originally Posted by Dignified Pauper

This thread got to involved. instead
*\o/*

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wow that is so gay.

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Originally Posted by Peegee

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Originally Posted by Juliebrenna

Well 50J may go to Neptune......lol ultimately because heat is transferred off the ball from friction and is released into the atmosphere. Some of earths heat is then lost into space - and ultimately minute amounts may make it all the way to Neptune :p. As far as your last question - newtons 2nd law.

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Does the second law explain why entropy only goes one way and not the other? Like why it's impossible for something colder to give energy to something hotter without work.

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Okay, listen up, and stay unazn, because entropy is a hard to understand topic.

First, something you have to realize that, like temperature, entropy is something we defined. So if it seems vague, that's only because in its original form, nobody who didn't take a university level thermodynamics course will understand (and a lot of who did still don't).

Entropy, in its simplest explination, is the measure of chaos in systems. Think of it as thus, take a container and pour sand in there with two different colors, both on either side, no crossover. Now you shake that container. The chance that the sand will come out mixed, with chaotic patterns, is far greater than the sand splitting in the same equal sides as before. That chaos is the form of entropy in this system. Shaking the container will only increase the entropy, and, at the best, the entropy will stay the same. Shaking the container will never make the sand more ordened. Therefore the entropy in a closed system can only increase or stay the same.

My third point, I say an closed system because that is a very important thing in entropy calculations. Entropy is often connected to temperature. As chaos is entropy, and molecules are most steady at low temperature, you can see why. Newton's third law states that the entropy of a crystal with perfect ordening, at a temperature of 0 Kelvin, is zero, because you exactly where each molecule is at every time. The system is ordened.

Now you ask, but why can't entropy decrease? I can take away heat through a fridge. That is because how you define the system. If you take the fridge and the room it came in, the entropy will only increase as it uses electrical power. (entropy usually takes into account the decay of higher forms of energy (work, electrical, etc) into lower ones (heat))

If you take the system inside the fridge, it cannot be a closed system, and the entropy of an open system can decrease.

This was another episode of Dennis teaches. Now go away.

"Jesus did it" is easier so that's what I'm going with. :D

http://i238.photobucket.com/albums/f...hu/ashinp4.jpg

I didn't know where else to post this sorry

Don't disgrace physics with your gay tendensies.

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Originally Posted by Aerith's Knight

Don't disgrace physics with your gay tendensies.

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but I'm a bi!fag

So basically entropy?

One of Doctor Manhattan's powers is 'reversing entropy', whatever that even means. What does it mean? Does he magic?

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Originally Posted by Peegee

One of Doctor Manhattan's powers is 'reversing entropy', whatever that even means. What does it mean? Does he magic?

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Impossible, but he'd do things like cool down objects without the heat going anywhere, create a Perpetuum mobile, and basically shatter the laws of physics wherever he goes.

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Originally Posted by Aerith's Knight

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Originally Posted by Peegee

One of Doctor Manhattan's powers is 'reversing entropy', whatever that even means. What does it mean? Does he magic?

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Impossible, but he'd do things like cool down objects without the heat going anywhere, create a Perpetuum mobile, and basically shatter the laws of physics wherever he goes.

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I like magic. BTW before I read that as his super powers, I thought he was just able to do anything that is within the realm of physics. For example it is theoretically possible to change atoms to other atoms by adding and removing electrons (whatever shut up) - but it's not possible to reverse entropy or transfer energy outside of the system.

This thread is now about Dr Manhattan.

So how about that big, blue penis?

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Originally Posted by NorthernChaosGod

So how about that big, blue penis?

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If I could reconstruct my body any way I want, I wonder what I would do.

I'd probably look something like that, but with a bigger penis.

I'd make myself not blue, probably before anything else.

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Originally Posted by NorthernChaosGod

I'd make myself not blue, probably before anything else.

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Blue is awesome. You can pretend to be sub-xerox

*yawn*

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Originally Posted by Laddy

*yawn*

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you are yawning at the idea of a blue man with big manliness. You are no gay to me!

No, just not impressed.

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Originally Posted by Laddy

No, just not impressed.

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knot gay!