Looking for an intelligent argument. (Terminal Velocity)

Answer the question.  What is terminal velocity?

Terminal velocity is reached when the acceleration relative to the Earth is zero. 

Quote from: TheEngineer on August 30, 2008, 10:19:43 PM

Terminal velocity is reached when the acceleration relative to the Earth is zero. 

so the FE model is a special case that must include the earth?

Quote from: cbarnett97 on August 30, 2008, 10:32:37 PM

Quote from: TheEngineer on August 30, 2008, 10:19:43 PM

Terminal velocity is reached when the acceleration relative to the Earth is zero. 

so the FE model is a special case that must include the earth?

That applies to the RE as well...

Ok... If this crap continues, I might have to lock this thread and declare FE as the winner. This dude (cbarnett97) just don't get it.

Quote from: e.Jack on August 31, 2008, 02:05:11 AM

Ok... If this crap continues, I might have to lock this thread and declare FE as the winner. This dude (cbarnett97) just don't get it.

Don't. It's entertaining.

I concur.  I never took physics, but I find it educational.

Never said which side i was leaning towards.  Both sides of the argument open the mind to possibilities, no matter your position on the subject.

Quote from: Stabler12 on August 31, 2008, 02:29:19 AM

Never said which side i was leaning towards.  Both sides of the argument open the mind to possibilities, no matter your position on the subject.

It isn't so much an argument as it is cbarnett97 being wrong and everyone else trying to teach him how physics works.

really everyone else? I just see the engineer only repeating one thing over and over, but if he is trying to teach me something then he has had many opportunities to use his vast knowledge of physics to properly teach me, since he has not done that it demonstrates he knows that he is wrong and he is just going to hang on to the one thing that makes him seem right to everyone else. I mean just look at his free body diagram, first he says that when you resolve the forces you get an unbalanced force then he magically adds the acceleration of the earth to balance it? that is not how it works. So if you want to believe theengineer then go ahead but at least understand what you are believing.

Quote from: cbarnett97 on August 31, 2008, 02:46:11 AM

really everyone else? I just see the engineer only repeating one thing over and over, but if he is trying to teach me something then he has had many opportunities to use his vast knowledge of physics to properly teach me, since he has not done that it demonstrates he knows that he is wrong and he is just going to hang on to the one thing that makes him seem right to everyone else. I mean just look at his free body diagram, first he says that when you resolve the forces you get an unbalanced force then he magically adds the acceleration of the earth to balance it? that is not how it works. So if you want to believe theengineer then go ahead but at least understand what you are believing.

I believe what TheEngineer says because he happens to be right.

A person is flown to an altitude above the earth that is totally covered by clouds and given an accelerometer and an airspeed indicator and he jumps out of the plane to determine the model. so when he jumps out he notices that the accelerometer shows an acceleration of 9.81m/s/s then it gradually goes to zero while his airspeed increases then remains static, so now he must ask himself either a) he was accelerated down while air resistance counteracted that until he reached a state of equalibrium or b) he remained stationary until the force from air resistance accelerated him up until he reached a state of equalibrium. from there he would need to test to see which one is correct. And as you can see at no time can that person relate what is happening to him with the surface of the earth. the acceleration of the earth is not in this system only the velocity of the air.

So please show me where the acceleration of the FE is known in this system so it can be included

Quote from: cbarnett97 on August 31, 2008, 02:57:54 AM

So please show me where the acceleration of the FE is known in this system so it can be included

Assuming the weather is calm and there are no other local variations in the movement of the air, the air is accelerating at the same rate as the Earth beneath it.

so why can we assume that is the case based upon the infomation given.

and what would an accelerometer show?

Quote from: cbarnett97 on August 31, 2008, 03:30:52 AM

so why can we assume that is the case based upon the infomation given.

If you really need that explained to you, your understanding of physics is even more hopelessly underdeveloped than I had supposed.

Quote from: cbarnett97 on August 31, 2008, 03:30:52 AM

and what would an accelerometer show?

Zero acceleration to begin with, gradually increasing to 9.8 m s^-2 when the observer reaches terminal velocity.

Show us the math for the accleration of the object

a_object=C_dpA{(a_airt)-v_object}²/2m

now show that it is the same as the RE model

Quote from: cbarnett97 on August 31, 2008, 03:50:07 AM

now show that it is the same as the RE model

http://en.wikipedia.org/wiki/Equivalence_principle

Try again. but this time do not run to wiki, think about what the model states.
EP will not work because that would only apply to what the person saw, the predictive power of a model is an entirely different matter.

Quote from: cbarnett97 on August 31, 2008, 03:59:10 AM

Try again. but this time do not run to wiki, think about what the model states.
EP will not work because that would only apply to what the person saw, the predictive power of a model is an entirely different matter.

In both cases, the air is accelerating at 9.8 m s^-2 upwards, with its initial velocity relative to the observer being zero. Assuming there is enough distance between the person and the ground for them to reach terminal velocity, their motion will be the same in both models.

nope in the RE model the velocity of the air is dependent upon the motion of the object, while in the FE model the velocity of the air is independent of the object

I just see the engineer only repeating one thing over and over

, but if he is trying to teach me something then he has had many opportunities to use his vast knowledge of physics to properly teach me, since he has not done that it demonstrates he knows that he is wrong

I mean just look at his free body diagram, first he says that when you resolve the forces you get an unbalanced force

then he magically adds the acceleration of the earth to balance it?

So if you want to believe theengineer then go ahead but at least understand what you are believing.