Hidemons

The state of Texas can split up into 5 different states anytime it wants to. http://www.snopes.com/history/american/texas.asp

I've always had a problem understanding the concept of equations that do not simply start with Y(x) = ...... This one for example: V(x+1) = V(x)+(g-(Cd/m)*v(x)^2)(ti+1-ti) is one that I have to make into a plot for this program called Matlab. (for computing stuff) Can someone explain this equation to me or enlighten me on the subject. How should I simplify this to make it more understandable?

It seems like all of these equations only have relevance after the entirety of the contact/collision is made. But is Force a vector? Can't an object fall with a force? = ma? This would require no contact to figure this out. If a 5000 kg train is moving from 10 mph to 30 mph in 2 seconds, its force upon impact on a wall would approx be 50,000 Kg*m/hr/s. This Force is calculated before any contact is made. Why couldn't I have used this logic in the previous example about the train, where say, it would accelerate to a speed in the course of a year, reducing acceleration to almost nothing.

Hey my name is Hidemons. Just found this forum and this thread. Am going to UT at the moment for Engineering. I have to say, this forum is blowing my mind! Its very easy to find very interesting and smart discussions in this place.

Where are you from? I thought it came out on the 8th? So the earliest would be at 12 tonight! Yea, was never a Star Trek fan, but I have high hopes for this movie.

Velocity is constant because it's my hypothetical situation in which one particle is moving very fast at constant speed and the other is say.... not moving at all (doesn't matter), initially. Are you saying that to calculate the force exerted on the second particle by the first, the only method is use information from both after and before the collision? Not just from initial information? If thats the case what would be the "t = time" in that formula for deriving Force from momentum? It seems kind of weird to me that a basic equations like the Force/momentum one doesn't work in some cases. In fact most cases. EDIT: Infact let me continue: If a train were to start at a velocity of 0 mph and then accelerate to 100 mph, does that mean over longer periods of time you would be impacted with less force when hit by the train?!!?!

Right, right, all the first stuff is fine and dandy but even when using momentum to calculate force exerted, there is no force exerted right? Since velocity is constant? This logic must be wrong, but why? Edit: Just want to make sure we're on the same page here: F = (final momentum – initial momentum)/t

You inadvertently presented an interesting idea there. There is a natural vacuum coming from space. This means that if the japanese figured out a method already for creating a structure tall enough to reach space then pressure differences could be used to lift the elevator box. Then once the elevator has reached the top of the structure, to go down, the top of the structure could be covered up and re-pressurized normally to get the elevator box to go down. It's like reverse gravity. Also, is making the elevator box strong enough to handle the pressure really that big of a deal? The leak-proofing is the biggest problem with the weight of the whole thing inevitably being ridiculous but I'm not sure what the people legitimately trying to design the elevator shaft are thinking how to create it anyway. so.

I'm in my beginning college physics class and I wonder why F = MA works sometimes. It get repeated over and over again from every grade since forever so I've just.... used it without question. Why is it that when particle 1 is moving at a constant 1 million mph and has mass of x (whatever) and collides with particle 2, that no force is applied to particle 2? Or why is this logic flawed?

Wait, answer the question though! I pretty sure gilbert meant Pneumatic tubes. I thought the hardest part of that Japanese Elevator is finding the right material for the cables. I read an article that said that those proposed nanotubes have to 5x stronger than they are right now to work. What is inefficient or bad about a Pneumatic elevator idea? The fact that the elevator tube has to be forever leak proof?