accereration 101

Wow Larry, thanks!
I didn't think I was crazy, I thought I had it right. So only from a maths perspective can acceleration be infinite, Right?

It was hard for me to imagine how in the real world that an action could happen and take no time to occur. It seemed like Dr. VanFlandern was playing some kind of game with me. I'm having real trouble figuring out how the Meta Model interpretes and uses the term infinity. Sometimes it is in relation to "real" things and then when you push on the issue it seems to only exist when it comes to the un-real or non-physical things like in maths and dimentions and such.


"(acceleration is NOT speed, but acceleration times time IS)."
I can see how in a mathematical model that you could divide a number an infinite amount of times but since we can't stop time I can't see how you could divide the time portion of acceleration down to any number we choose adn have "NO" time present. Here is a good question I have not thought about?

What is the speed of time?

But Dr. VanFlandern told me he wasn't playing any games, why are you trying to cover for him??

Just learning!
Magoo

Lets just keep on the topic OK? Acceleration in particle accelerators gets to a point where velocity and acceleration are constant. This also happens in gravity fields right? How is this resolved if A=V/T?

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Magoo]
What is the speed of time?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

Not enough information.

The Physics definition of speed is "the rate of change of position with respect to time".

If you tell me what the position of time is at several different times, then I can answer the question. But you'll have to tell me what "the position of time" means, first

Regards,
LB

From Jim,

Lets just keep on the topic OK? Acceleration in particle accelerators gets to a point where velocity and acceleration are constant. This also happens in gravity fields right? How is this resolved if A=V/T?

Jim,

When a particle rotates it has a constant velocity tangent to its path and a constant centripetal acceleration perpendicular to the path. There is no linear acceleration, it is zero. If the centripetal acceleration vanishes, the particle will move at a constant linear speed. a=v/t does not apply but a = (v x v) /r where a is the centripetal acceleration keeping the particle on a circular path.

As far as dividing the speed of an accelerating particle on linear motion in infinitesimal increments you can theoritically do that but Patrick is right although may not appear to be making a clear statement, it does not matter how small you make the increment, you can never increase the acceleration beyond that which causes the speed the particle is going at.

In Kinematics, which is the study of motion, you can envision any acceleration you like. However, in Dynamics which is reality, Newton's law comes into play to relate force and acceleration. Then, infinite acceleration means infinite force and vice versa. Einstein put an upper limit in the energy of physical systems with E=mc^2. An infinite acceleration would imply infinite energy which violates that rule. It has been shown that as particle speeds approach the speed of light, their acceleration decreases asymptotically to a value given by a relativistic formula.

I do not see any point for this debate. The term "infinite acceleration" can be used by an abstract mathemetician but should not be part of the vocabulary of a physisist. If it is, then that physisist is indeed very confused.

Time to fix some cars.

So then there are different kinds of acceleration? The point of kicking this around is there seems to be a lot of confusion about what effects can be observed as a result of acceleration.

From Jim:

So then there are different kinds of acceleration? The point of kicking this around is there seems to be a lot of confusion about what effects can be observed as a result of acceleration.

---

For a general motion along a curved path there are two kinds of acceleration: tangential acceleration and normal acceleration. When you make a fast turn with your car of radius r at a speed v those two are

tangential=dv/dt

centripetal=v^2/r

and v=r x omega, omega = angular speed

As you can see, even if the tangential speed is constant and the tangential acceleration is then zero, there is always centripetal acceleration. This is an important result in Kinematics: Every motion on a curved path, whether uniform (omega=constant) of not, is an accelerated motion.

Newtonian mechanics ahve been blamed for this mess, the fact of decomposing motion this way. It's done in order to work with polar coordinates and solve problems like the the two-body problem. If you work with cartesian coordinates, a particle moving in 2-d has two components of acceleration, one along the y and one along the x axis. But since the gravity force is a central force, polar coordinates are prefered and that confuses people.

Time to fix some cars, it's getting late customers getting angry.