Parachutes

Once again Inertial mass by definition is an objects resistance to being accelerated. And what causes acceleration? a force so by definition inertial mass measures a required force. not just its mass, if you want to know its mass you calculate its rest mass and yes that unit would only be kg.

"Inertial mass. This is mainly defined by Newton's law, the all-too-famous F = ma, which states that when a force F is applied to an object, it will accelerate proportionally, and that constant of proportion is the mass of that object. In very concrete terms, to determine the inertial mass, you apply a force of F Newtons to an object, measure the acceleration in m/s2, and F/a will give you the inertial mass m in kilograms."

The nice thing about math is you can calculate any unknown as long as you know some of the items in the equation, they are saying the same thing just going about it from the opposite direction, I am using the mass to calculate toe force and they are using the force to calculate the mass

The nice thing about math is you can calculate any unknown as long as you know some of the items in the equation, they are saying the same thing just going about it from the opposite direction, I am using the mass to calculate toe force and they are using the force to calculate the mass

But you are only using the mass in your equation. 

Quote from: sokarul on August 25, 2007, 10:45:49 PM

No I was right.  But actually you were also right if you were talking about a RE.  I was talking about a FE. 

No, you were wrong in both situations.

Umm no.  
In the fe
Terminal "velocity" is actually terminal acceleration right?  This acceleration would be at 9.8m/s² right?
But it took you longer to reach the 9.8m/s² right?  So the earths velocity compared to yours is faster right?
So when you pull the chute you have to gain velocity as to not hit the earth at 200kph right?  
So how does one speed up compared to the earth velocity while accelerating slower?
When a person on the fe hits the earth they are nto accelerating right?  So thus they have to be accelerating at 9.8m/s² too right?  
So in the fe a person acceleration would start at zero and then clime to 9.8m/2²  to hit terminal "velocity".  The they would pull their chute and be accelerated to a number much greater than 9.8m/s and than slowly deaccelerate back to 9.8m/s².  Otherwise they would eventually start to gain altitude.  
Do you understand?  

I will make it this much easier for you, the only opposing force to the air resistance in the FE model would be the counter force measured in newtons that is caused by the mass's resistance to being accelerated that I  represented with the symbol "I" in the equation. Now please show me how my equation was flawed.

In the fe
Terminal "velocity" is actually terminal acceleration right?

Yes.

This acceleration would be at 9.8m/s² right?

No.

But it took you longer to reach the 9.8m/s² right?

Longer than what?

So the earths velocity compared to yours is faster right?

Yes.

So when you pull the chute you have to gain velocity as to not hit the earth at 200kph right? 

Yes.

So how does one speed up compared to the earth velocity while accelerating slower?

You are not going faster than the earth.

When a person on the fe hits the earth they are nto accelerating right?

With respect to the earth, yes.

So thus they have to be accelerating at 9.8m/s² too right? 

No.

So in the fe a person acceleration would start at zero and then clime to 9.8m/2²  to hit terminal "velocity".  The they would pull their chute and be accelerated to a number much greater than 9.8m/s and than slowly deaccelerate back to 9.8m/s².

No.

  Otherwise they would eventually start to gain altitude.   

No.

Do you understand? 

Your logic, no.

I will make it this much easier for you, the only opposing force to the air resistance in the FE model would be the counter force measured in newtons that is caused by the mass's resistance to being accelerated that I  represented with the symbol "I" in the equation. Now please show me how my equation was flawed.

You have mass equal to a force.

"When we look at the other side of the equation, ma, then we are talking about the object's inertial mass - its resistance to a change in its state of motion, that is, its resistance to being accelerated. This mass is a measure of how much inertia must be accelerated.
 

Since we can experimentally determine that all freely-falling bodies experience the same acceleration, that is, a = -g, we have proof that
 
"A body's Inertial Mass is
is measure of how strongly the body is accelerated (by A) by a given force.
It is the m_i in Newton's 2nd-law:
Force = m_i A"

"Some physicists accordingly distinguish gravitational mass m_g from inertial mass m_i"

Still haven't found anything about mass or inertial mass being calculated in newtons.

Quote from: cbarnett97 on August 25, 2007, 10:58:23 PM

I will make it this much easier for you, the only opposing force to the air resistance in the FE model would be the counter force measured in newtons that is caused by the mass's resistance to being accelerated that I  represented with the symbol "I" in the equation. Now please show me how my equation was flawed.

You have mass equal to a force.

that is why i changed it just for you to be a force, you can go ahead an read a physics textbook and you will learn all about it, but if it will make you happy i can remove it since according to you it should not be there, but that will only help prove my point since the acceleration in the same direction of the earth would only increase faster. Even though the equation would then be wrong

that is why i changed it just for you to be a force, you can go ahead an read a physics textbook and you will learn all about it, but if it will make you happy i can remove it since according to you it should not be there, but that will only help prove my point since the acceleration in the same direction of the earth would only increase faster. Even though the equation would then be wrong

Let me ask you this:  What acceleration did you use for your original 'I'?

Quote from: cbarnett97 on August 25, 2007, 11:10:13 PM

that is why i changed it just for you to be a force, you can go ahead an read a physics textbook and you will learn all about it, but if it will make you happy i can remove it since according to you it should not be there, but that will only help prove my point since the acceleration in the same direction of the earth would only increase faster. Even though the equation would then be wrong

Let me ask you this:  What acceleration did you use for your original 'I'?

Well being that I have not run any numbers I have not put any numbers into it, but you can use any number you want because it is a proportion, but If I were to run some numbers I would use a very small acceleration in this case because I am only trying to find the force needed to get the object moving.

So any acceleration will hold true?

it is a direct proportionality, but to properly solve the problem you would need to use numerical modeling for the air resistance but yes you just need to know the minimum force to cause the object to accelerate and that will be that objects resistance to being moved, any more force will just increase the acceleration which is not what we are trying to calculate

Quote from: sokarul on August 25, 2007, 10:57:11 PM

In the fe
Terminal "velocity" is actually terminal acceleration right?

Yes.

Quote

This acceleration would be at 9.8m/s² right?

No.

Quote

But it took you longer to reach the 9.8m/s² right?

Longer than what?

Quote

So the earths velocity compared to yours is faster right?

Yes.

Quote

So when you pull the chute you have to gain velocity as to not hit the earth at 200kph right? 

Yes.

Quote

So how does one speed up compared to the earth velocity while accelerating slower?

You are not going faster than the earth.

Quote

When a person on the fe hits the earth they are nto accelerating right?

With respect to the earth, yes.

Quote

So thus they have to be accelerating at 9.8m/s² too right? 

No.

Quote

So in the fe a person acceleration would start at zero and then clime to 9.8m/2²  to hit terminal "velocity".  The they would pull their chute and be accelerated to a number much greater than 9.8m/s and than slowly deaccelerate back to 9.8m/s².

No.

Quote

  Otherwise they would eventually start to gain altitude.   

No.

Quote

Do you understand? 

Your logic, no.

Setting the skydives POV as the FOR when he is at terminal "velocity" he sees the earth coming at him at 200kph.  He does not see the earth accelerating.  So he HAS to be matched to the earths acceleration.  So this makes his acceleration have to be 9.8m/s² too, so he is not accelerating towards the earth.  Do you understand?  The earth velocity will be faster than the skydiver though, in a general FOR where both are accelerating.  But the skydiver doesn't want to hit the earth at 200kph so he pulls his chute.  His chute slows him down in his reference frame to lets say, 20kph.  But in our general FOR the earth was moving faster than him so he has to accelerate to better match the speed of the earth.  So in other words he has to out accelerate the earth.  Thus he has to accelerate in a general FOR or just de accelerate in his FOR.  So to deaccelerate in his FOR he must actually accelerate in the general FOR, thus he has to increase his velocity so when he hits the ground it will be moving at some velocity x while he has the velocity x - 20 kph.  
And you think my logic is messed up.      

So if the skydiver's acceleration is 9.8m/s^2 and the earth's acceleration is 9.8m/s^2, how will they ever meet?

So if the skydiver's acceleration is 9.8m/s^2 and the earth's acceleration is 9.8m/s^2, how will they ever meet?

That was my original point, and that is what is wrong with the FE theory in this case.

So if the skydiver's acceleration is 9.8m/s^2 and the earth's acceleration is 9.8m/s^2, how will they ever meet?

The skydivers acceleration went to zero when he jumped out of the plane.  Thus the earth gains on him.  As the air around him accelerates, it accelerates him.  But this is no where near 9.8m/s² yet.  Terminal velocity is actually when his acceleration finally reaches the earths acceleration.  So he does not accelerate towards it.   How could he stop accelerating towards the earth is he never even matches the earth's acceleration?  

Quote from: TheEngineer on August 25, 2007, 11:29:31 PM

So if the skydiver's acceleration is 9.8m/s^2 and the earth's acceleration is 9.8m/s^2, how will they ever meet?

That was my original point, and that is what is wrong with the FE theory in this case.

Did you read my original explanation?

The skydivers acceleration went to zero when he jumped out of the plane.  Thus the earth gains on him.  As the air around him accelerates, it accelerates him.  But this is no where near 9.8m/s² yet.  Terminal velocity is actually when his acceleration finally reaches the earths acceleration.  So he does not accelerate towards it.   

Now do you see how your original explanation was wrong?

How could he stop accelerating towards the earth is he never even matches the earth's acceleration? 

Did you read my original explanation?

Quote from: sokarul on August 25, 2007, 11:33:57 PM

The skydivers acceleration went to zero when he jumped out of the plane.  Thus the earth gains on him.  As the air around him accelerates, it accelerates him.  But this is no where near 9.8m/s² yet.  Terminal velocity is actually when his acceleration finally reaches the earths acceleration.  So he does not accelerate towards it.   

Now do you see how your original explanation was wrong?

I guess you missed this post.

No the whole thing I typed was wrong.  Sadly, I get it now.  At terminal "velocity" your acceleration would match the earths, 9.8m/s².  This same acceleration is what allows a person to not see air moving faster that 200kph.  The earth would have a greater velocity than you and thus eventually hit you.  But there is no terminal velocity in the FET, it would be called terminal acceleration. 

But we aren't arguing that anymore. 
We are arguing how you think that by accelerating slower than something you can safely land on it. 
So, you you understand how your argument is wrong? 

I guess no one remembered when I said that any experiment or observation of this kind (remember the lollipop example) will not yield you the results you desire.  The EP (I sure as hell hope my parachute is larger than a closet!) assures us that you would not be able to tell the difference between 'gravity' and acceleration.

Now, Gulliver is correct (gasp!) in that you are taking the air to be a rigid body that does not escape the canopy.  You would have the greatest acceleration only when (unpowered) you were rigidly connected to the Earth.  Such as if your chute got stuck in some trees and you were left hanging, accelerating at 9.8m/s^2.  However, when you are in the airplane you are accelerating at the same rate as the Earth.  Once you jump out of the plane, you begin to decelerate.  There is a point at which you reach terminal velocity, at which your acceleration towards the earth is zero, but you still have a certain velocity.  As the earth continues to accelerate, it pushes on your chute with a greater force, thus allowing you to maintain your relative velocity to the Earth.  Now, since the air is not a rigid body, it escapes around your chute, ensuring that your current upwards velocity is just slightly less than that of the Earth.  Therefore, you slowly approach the Earth, and land nice and easy.

yes I read it but your mistakes are this: first you invoke EP which will only apply when asked "what did you feel" and it is not valid when using a model to predict behavior. Secondly you assume that air can provide only a very minimal force when, and lastly you assume that since the system is not %100 efficient then it will never be accelerated. I hope that helps you

yes I read it but your mistakes are this: first you invoke EP which will only apply when asked "what did you feel" and it is not valid when using a model to predict behavior. Secondly you assume that air can provide only a very minimal force when, and lastly you assume that since the system is not %100 efficient then it will never be accelerated. I hope that helps you

"What did you feel?"  What the hell are you talking about?  The EP is great at finding a model to predict behavior.  That's how much of the FE stuff works.  When did I say the air can only provide a 'very minimal' force?  I assume the system is not 100% efficient because it is not.  I hope that helps you.

Quote from: cbarnett97 on August 25, 2007, 11:40:51 PM

yes I read it but your mistakes are this: first you invoke EP which will only apply when asked "what did you feel" and it is not valid when using a model to predict behavior. Secondly you assume that air can provide only a very minimal force when, and lastly you assume that since the system is not %100 efficient then it will never be accelerated. I hope that helps you

"What did you feel?"  What the hell are you talking about?  The EP is great at finding a model to predict behavior.  That's how much of the FE stuff works.  When did I say the air can only provide a 'very minimal' force?  I assume the system is not 100% efficient because it is not.  I hope that helps you.

Ok by not answering my post I'm going to assume you figured out you were wrong. 

We are arguing how you think that by accelerating slower than something you can safely land on it. 
So, you you understand how your argument is wrong? 

I find it very funny that someone who claims to 'know' the EP is arguing the whole parachute idea in the first place.

Edit:  Thinking about it simpler.

Ok by not answering my post I'm going to assume you figured out you were wrong. 

"Patience is a virtue often lost."

Quote from: cbarnett97 on August 25, 2007, 11:40:51 PM

yes I read it but your mistakes are this: first you invoke EP which will only apply when asked "what did you feel" and it is not valid when using a model to predict behavior. Secondly you assume that air can provide only a very minimal force when, and lastly you assume that since the system is not %100 efficient then it will never be accelerated. I hope that helps you

"What did you feel?"  What the hell are you talking about?  The EP is great at finding a model to predict behavior.  That's how much of the FE stuff works.  When did I say the air can only provide a 'very minimal' force?  I assume the system is not 100% efficient because it is not.  I hope that helps you.

And the FE theory is very flawed so therefore my statement stands, And I agree that the system is not %100 efficient but I disagree with your conclusion

And the FE theory is very flawed so therefore my statement stands, And I agree that the system is not %100 efficient but I disagree with your conclusion

And yet you have failed to provide this flaw, as it sure is not in this thread.

Quote from: sokarul on August 26, 2007, 12:08:29 AM

Ok by not answering my post I'm going to assume you figured out you were wrong. 

"Patience is a virtue often lost."

First of all you logged off for a little bit.  

Quote from: sokarul on August 25, 2007, 11:40:00 PM

We are arguing how you think that by accelerating slower than something you can safely land on it. 
So, you you understand how your argument is wrong? 

No, we are arguing how you think that by accelerating at the same rate as something (from the same initial velocity, no less!)  you can reach it.

Think about it like this:  You are in your car, you step on the gas and start to accelerate.  You and your front bumper have the same acceleration.  Using your logic, you would slowly approach the bumper.  That would make long trips very uncomfortable.

I find it very funny that someone who claims to 'know' the EP is arguing the whole parachute idea in the first place.

Ok.  
If you jump out of a plane in the FE you will loose your acceleration while the earth will not, right?

so what force counteracts the air resistance to produce a state of equalibrium so we achieve a terminal velocity? and therefore have a model that reflect reality

so what force counteracts the air resistance to produce a state of equalibrium so we achieve a terminal velocity? and therefore have a model that reflect reality

No force.  Once you reach terminal acceleration, the air cannot push and harder.