Parachutes

Quote from: divito on August 27, 2007, 07:59:37 PM

Quote from: Gulliver on August 27, 2007, 07:43:50 PM

Of course, you impeach FE very well with your analogy. Did you intend that?

Since the FE moves up like your hand in the water and since the water flows off over the edge, we're faced with a renewed challenge to FE on how it retains its atmosphere.

Figures. I'll have to think of something. And I have to find time to work out those gravitational numbers too.

Quote from: cbarnett97 on August 27, 2007, 07:53:36 PM

You cannot say that a ferrari and a pinto accelerate at the same rate because they both start at zero and then end up at 60. and not once did I ever try to relate him to the surface of the earth, I have only talked about the forces acting upon the parachutist.

In RE, parachuter accelerates down to stationary Earth. Air provides resistance.

In FE, Earth accelerates up to stationary parachuter. Air provides resistance.

yes air provides resistance in both cases but in RE you get a gravitaional force acting upon the body to counteract the force caused by air resistance so we can get a state of equalibrium (terminal velocity) in FE you only get the force caused by air resistance so you can never reach a state of equalibrium so oyu end up with a net force in the same direction as the accelerating earth.

Er, I'm pretty sure you don't accelerate at 9.8m/s² with a parachute, even in RE.

See??
Its relevant.  Divitio's thought process was wrong as is Mr. Ireland.  TheEngineer's was until he realized it.  I'm sure some other peoples are wrong as well.     
Them being relative acceleration does not matter. 

Quote from: cbarnett97 on August 27, 2007, 08:04:50 PM

Quote from: divito on August 27, 2007, 07:59:37 PM

Quote from: Gulliver on August 27, 2007, 07:43:50 PM

Of course, you impeach FE very well with your analogy. Did you intend that?

Since the FE moves up like your hand in the water and since the water flows off over the edge, we're faced with a renewed challenge to FE on how it retains its atmosphere.

Figures. I'll have to think of something. And I have to find time to work out those gravitational numbers too.

Quote from: cbarnett97 on August 27, 2007, 07:53:36 PM

You cannot say that a ferrari and a pinto accelerate at the same rate because they both start at zero and then end up at 60. and not once did I ever try to relate him to the surface of the earth, I have only talked about the forces acting upon the parachutist.

In RE, parachuter accelerates down to stationary Earth. Air provides resistance.

In FE, Earth accelerates up to stationary parachuter. Air provides resistance.

yes air provides resistance in both cases but in RE you get a gravitaional force acting upon the body to counteract the force caused by air resistance so we can get a state of equalibrium (terminal velocity) in FE you only get the force caused by air resistance so you can never reach a state of equalibrium so oyu end up with a net force in the same direction as the accelerating earth.

I don't know how to explain it any more clearly. The effect of RE's gravity is mimicked by the effect of the FE's acceleration of the Earth's surface toward the parachutist. You must include this effect in the FE model in order to have a complete solution.

RE =>  m*g = F_D

FE =>  m*a = F_D

Just solve for velocity from the drag equation.

How? If i am water skiing do I need to hang on to the tow rope for the boat to accelerate me, I cant just stand in front of it and let the wind push me I need to be connected to the system for it to accelerate me

Quote from: cbarnett97 on August 27, 2007, 08:13:58 PM

How? If i am water skiing do I need to hang on to the tow rope for the boat to accelerate me, I cant just stand in front of it and let the wind push me I need to be connected to the system for it to accelerate me

You're trying to equate the force of an accelerating Earth to a boat? One is a big, flat expanse of matter (FE obviously..). The other is an aerodynamic craft.

Quote from: TheEngineer on August 27, 2007, 06:53:44 PM

RE =>  m*g = F_D

FE =>  m*a = F_D

Just solve for velocity from the drag equation.

Quote from: Gulliver on August 27, 2007, 08:11:00 PM

Quote from: cbarnett97 on August 27, 2007, 08:04:50 PM

Quote from: divito on August 27, 2007, 07:59:37 PM

Quote from: Gulliver on August 27, 2007, 07:43:50 PM

Of course, you impeach FE very well with your analogy. Did you intend that?

Since the FE moves up like your hand in the water and since the water flows off over the edge, we're faced with a renewed challenge to FE on how it retains its atmosphere.

Figures. I'll have to think of something. And I have to find time to work out those gravitational numbers too.

Quote from: cbarnett97 on August 27, 2007, 07:53:36 PM

You cannot say that a ferrari and a pinto accelerate at the same rate because they both start at zero and then end up at 60. and not once did I ever try to relate him to the surface of the earth, I have only talked about the forces acting upon the parachutist.

In RE, parachuter accelerates down to stationary Earth. Air provides resistance.

In FE, Earth accelerates up to stationary parachuter. Air provides resistance.

yes air provides resistance in both cases but in RE you get a gravitaional force acting upon the body to counteract the force caused by air resistance so we can get a state of equalibrium (terminal velocity) in FE you only get the force caused by air resistance so you can never reach a state of equalibrium so oyu end up with a net force in the same direction as the accelerating earth.

I don't know how to explain it any more clearly. The effect of RE's gravity is mimicked by the effect of the FE's acceleration of the Earth's surface toward the parachutist. You must include this effect in the FE model in order to have a complete solution.

How? If i am water skiing do I need to hang on to the tow rope for the boat to accelerate me, I cant just stand in front of it and let the wind push me I need to be connected to the system for it to accelerate me

Quote from: divito on August 27, 2007, 06:59:48 PM

Er, I'm pretty sure you don't accelerate at 9.8m/s² with a parachute, even in RE.

Quote from: sokarul on August 27, 2007, 08:01:17 PM

See??
Its relevant.  Divitio's thought process was wrong as is Mr. Ireland.  TheEngineer's was until he realized it.  I'm sure some other peoples are wrong as well.     
Them being relative acceleration does not matter. 

If that statement is wrong, you equate the air and parachute to a pole connected to the Earth. If anything, you'll reach 9.8m/s² after the initial deployment of the parachute, and I can't imagine it lasting for more than a few seconds. To which the Earth will significantly gain on the skydiver's position.

So now air can recreate the force of gravity? so do you stand by your statement that it can never accelerate you to 9.8m²

Quote from: cbarnett97 on August 27, 2007, 08:13:58 PM

Quote from: Gulliver on August 27, 2007, 08:11:00 PM

Quote from: cbarnett97 on August 27, 2007, 08:04:50 PM

Quote from: divito on August 27, 2007, 07:59:37 PM

Quote from: Gulliver on August 27, 2007, 07:43:50 PM

Of course, you impeach FE very well with your analogy. Did you intend that?

Since the FE moves up like your hand in the water and since the water flows off over the edge, we're faced with a renewed challenge to FE on how it retains its atmosphere.

Figures. I'll have to think of something. And I have to find time to work out those gravitational numbers too.

Quote from: cbarnett97 on August 27, 2007, 07:53:36 PM

You cannot say that a ferrari and a pinto accelerate at the same rate because they both start at zero and then end up at 60. and not once did I ever try to relate him to the surface of the earth, I have only talked about the forces acting upon the parachutist.

In RE, parachuter accelerates down to stationary Earth. Air provides resistance.

In FE, Earth accelerates up to stationary parachuter. Air provides resistance.

yes air provides resistance in both cases but in RE you get a gravitaional force acting upon the body to counteract the force caused by air resistance so we can get a state of equalibrium (terminal velocity) in FE you only get the force caused by air resistance so you can never reach a state of equalibrium so oyu end up with a net force in the same direction as the accelerating earth.

I don't know how to explain it any more clearly. The effect of RE's gravity is mimicked by the effect of the FE's acceleration of the Earth's surface toward the parachutist. You must include this effect in the FE model in order to have a complete solution.

How? If i am water skiing do I need to hang on to the tow rope for the boat to accelerate me, I cant just stand in front of it and let the wind push me I need to be connected to the system for it to accelerate me

Let's make sure that we the analogy straight.

In RE:
A motorboat accelerates a skier toward the shore.
The motorboat is gravity.
The skier is the parachutist.
The shore is the surface of the Earth.

In FE:
The shore accelerates toward the skier
The acceleration of the shore is the UA.
The boat accelerates away from the shore toward the skier pulling the shore with it is the UA
The shore is the surface of the Earth.
The skier is the parachutist.

In both models the relative velocities, the distance between the shore and the skier, and the time the skier reaches the shore are all the same.
The forces acting upon the skier are not equal so the skiers reach the shore at different times and at different relative velocities
My proof stands. Needs Improvement

Let's make sure that we the analogy straight.

In RE:
A motorboat accelerates a skier toward the shore.
The motorboat is gravity.
The skier is the parachutist.
The shore is the surface of the Earth.

In FE:
The shore accelerates toward the skier
The acceleration of the shore is the UA.
The boat accelerates away from the shore toward the skier pulling the shore with it is the UA
The shore is the surface of the Earth.
The skier is the parachutist.

In both models the relative velocities, the distance between the shore and the skier, and the time the skier reaches the shore are all the same.
The forces acting upon the skier are not equal so the skiers reach the shore at different times and at different relative velocities
My proof stands. Needs Improvement

Fixed it for you

Quote from: Gulliver on August 27, 2007, 08:20:50 PM

Quote from: cbarnett97 on August 27, 2007, 08:13:58 PM

Quote from: Gulliver on August 27, 2007, 08:11:00 PM

Quote from: cbarnett97 on August 27, 2007, 08:04:50 PM

Quote from: divito on August 27, 2007, 07:59:37 PM

Quote from: Gulliver on August 27, 2007, 07:43:50 PM

Of course, you impeach FE very well with your analogy. Did you intend that?

Since the FE moves up like your hand in the water and since the water flows off over the edge, we're faced with a renewed challenge to FE on how it retains its atmosphere.

Figures. I'll have to think of something. And I have to find time to work out those gravitational numbers too.

Quote from: cbarnett97 on August 27, 2007, 07:53:36 PM

You cannot say that a ferrari and a pinto accelerate at the same rate because they both start at zero and then end up at 60. and not once did I ever try to relate him to the surface of the earth, I have only talked about the forces acting upon the parachutist.

In RE, parachuter accelerates down to stationary Earth. Air provides resistance.

In FE, Earth accelerates up to stationary parachuter. Air provides resistance.

yes air provides resistance in both cases but in RE you get a gravitaional force acting upon the body to counteract the force caused by air resistance so we can get a state of equalibrium (terminal velocity) in FE you only get the force caused by air resistance so you can never reach a state of equalibrium so oyu end up with a net force in the same direction as the accelerating earth.

I don't know how to explain it any more clearly. The effect of RE's gravity is mimicked by the effect of the FE's acceleration of the Earth's surface toward the parachutist. You must include this effect in the FE model in order to have a complete solution.

How? If i am water skiing do I need to hang on to the tow rope for the boat to accelerate me, I cant just stand in front of it and let the wind push me I need to be connected to the system for it to accelerate me

Let's make sure that we the analogy straight.

In RE:
A motorboat accelerates a skier toward the shore.
The motorboat is gravity.
The skier is the parachutist.
The shore is the surface of the Earth.

In FE:
The shore accelerates toward the skier
The acceleration of the shore is the UA.
The boat accelerates away from the shore toward the skier pulling the shore with it is the UA
The shore is the surface of the Earth.
The skier is the parachutist.

In both models the relative velocities, the distance between the shore and the skier, and the time the skier reaches the shore are all the same.
The forces acting upon the skier are not equal so the skiers reach the shore at different times and at different relative velocities
My proof stands. Needs Improvement

Fixed it so its wrong for you.

I am not saying it, you are ae equating the acceleration of the earth to be tha same as gravity when the earth itself is unable to accelerate the person, the only thing that can accelerate him would be his air resistance, and that acceleration would only speed him up to match the acceleration of the earth to the point where his relative position to the surface of the earth would not change. Imagine this: go to a river near you with a buddy, have him get on a raft and let him accelerate to the same speed as the river. Then get a distance ahead of him and then you get into the river on your own raft and just the the current accelerate you. now ask yourself "will he ever catch you?" and the answer will be yes if you  are close enough to where he could catch you while the river was accelerating you but if oyu were far enough away initially he would never catch you because you are both traveling at the same rate.

I am not saying it.

You are equating the acceleration of the earth to be the same as gravity when the earth itself is unable to accelerate the person.

The only thing that can accelerate him would be his air resistance.

That acceleration would only speed him up to match the acceleration of the earth to the point where his relative position to the surface of the earth would not change.

I am not saying it, you are ae equating the acceleration of the earth to be tha same as gravity when the earth itself is unable to accelerate the person, the only thing that can accelerate him would be his air resistance, and that acceleration would only speed him up to match the acceleration of the earth to the point where his relative position to the surface of the earth would not change. Imagine this: go to a river near you with a buddy, have him get on a raft and let him accelerate to the same speed as the river. Then get a distance ahead of him and then you get into the river on your own raft and just the the current accelerate you. now ask yourself "will he ever catch you?" and the answer will be yes if you  are close enough to where he could catch you while the river was accelerating you but if oyu were far enough away initially he would never catch you because you are both traveling at the same rate.

I am not saying it, you are ae equating the acceleration of the earth to be tha same as gravity when the earth itself is unable to accelerate the person, the only thing that can accelerate him would be his air resistance, and that acceleration would only speed him up to match the acceleration of the earth to the point where his relative position to the surface of the earth would not change. Imagine this: go to a river near you with a buddy, have him get on a raft and let him accelerate to the same speed as the river. Then get a distance ahead of him and then you get into the river on your own raft and just the the current accelerate you. now ask yourself "will he ever catch you?" and the answer will be yes if you  are close enough to where he could catch you while the river was accelerating you but if oyu were far enough away initially he would never catch you because you are both traveling at the same rate.

ah hell you are right I was doing the same thing you guys are doing, I was mixing the two models. you are correct he would still land but that will still not match reality which is my whole point to begin with the accelerations will not match up to reality

Quote from: cbarnett97 on August 27, 2007, 09:18:00 PM

ah hell you are right I was doing the same thing you guys are doing, I was mixing the two models. you are correct he would still land but that will still not match reality which is my whole point to begin with the accelerations will not match up to reality

You need to tell us the reason that the accelerations will not match up to reality.

Quote from: Gulliver on August 27, 2007, 09:22:42 PM

Quote from: cbarnett97 on August 27, 2007, 09:18:00 PM

ah hell you are right I was doing the same thing you guys are doing, I was mixing the two models. you are correct he would still land but that will still not match reality which is my whole point to begin with the accelerations will not match up to reality

You need to tell us the reason that the accelerations will not match up to reality.

the forces do not equate. in RE we are sped up and that is causes the increasing air resistance so the force of us speeding up cna me matched in an equal and opposite direction, While in FE  the increasing air resistance comes from the air speeding up around us so instead of getting a balance of forces we get a net force that acts on us so our acceleration will never be zero, the best that can be had is that our acceleration will match that of the air.
Or simply put,
RE: F=mg-R
FE: F=-R
Now who can tell us the difference between these 2

Why do you keep ignoring my post with the terminal velocity equations?

ewe are not relating the distance, we are comparing forces acting upon a body. and when you look at the forces acting upon the body there is no mg type force in FE. you must try to not think of what happens in real life and look at what the model predicts will happen.

Quote from: cbarnett97 on August 28, 2007, 03:01:47 PM

ewe are not relating the distance, we are comparing forces acting upon a body. and when you look at the forces acting upon the body there is no mg type force in FE. you must try to not think of what happens in real life and look at what the model predicts will happen.

We are talking about comparing forces that are affecting the distance between the parachutist and the surface. You're choosing, incorrectly, to ignore the effect of the Force accelerating the FE.

Quote from: Gulliver on August 28, 2007, 03:17:51 PM

Quote from: cbarnett97 on August 28, 2007, 03:01:47 PM

ewe are not relating the distance, we are comparing forces acting upon a body. and when you look at the forces acting upon the body there is no mg type force in FE. you must try to not think of what happens in real life and look at what the model predicts will happen.

We are talking about comparing forces that are affecting the distance between the parachutist and the surface. You're choosing, incorrectly, to ignore the effect of the Force accelerating the FE.

no we are not we are just talking about the forces that are acting on his body, once we know what these forces are we then can relate it to the earth.

Quote from: cbarnett97 on August 28, 2007, 03:19:48 PM

Quote from: Gulliver on August 28, 2007, 03:17:51 PM

Quote from: cbarnett97 on August 28, 2007, 03:01:47 PM

ewe are not relating the distance, we are comparing forces acting upon a body. and when you look at the forces acting upon the body there is no mg type force in FE. you must try to not think of what happens in real life and look at what the model predicts will happen.

We are talking about comparing forces that are affecting the distance between the parachutist and the surface. You're choosing, incorrectly, to ignore the effect of the Force accelerating the FE.

no we are not we are just talking about the forces that are acting on his body, once we know what these forces are we then can relate it to the earth.

You're welcome to do so. Take it in whatever steps you need.

I found it quite simple to go with the relative model, but it does take an open mind.

Let me know when you put mg in the FE equation.

Quote from: Gulliver on August 28, 2007, 03:25:27 PM

Quote from: cbarnett97 on August 28, 2007, 03:19:48 PM

Quote from: Gulliver on August 28, 2007, 03:17:51 PM

Quote from: cbarnett97 on August 28, 2007, 03:01:47 PM

ewe are not relating the distance, we are comparing forces acting upon a body. and when you look at the forces acting upon the body there is no mg type force in FE. you must try to not think of what happens in real life and look at what the model predicts will happen.

We are talking about comparing forces that are affecting the distance between the parachutist and the surface. You're choosing, incorrectly, to ignore the effect of the Force accelerating the FE.

no we are not we are just talking about the forces that are acting on his body, once we know what these forces are we then can relate it to the earth.

You're welcome to do so. Take it in whatever steps you need.

I found it quite simple to go with the relative model, but it does take an open mind.

Let me know when you put mg in the FE equation.

there is no mg in the FE model. FE'ers need to add it to make sure they are correct even though it violates their model. Then they will just claim that it is because of the EP so if you want to follow then that is fine by me but it does not make them any more right

where does mg come from. now look at the FE model carefully, when you jump out of a plane you are no longer being accelerated by the FE so it catches up to you. So once again do not think of reality when you look at the problem. The FE model is not an accurate model for predicting behavior because of this simple fact of the missing mg.