Mythbusters to take on "the plane and the treadmill" conundrum?

[Fraggable]

Look man according to the wording of the question, the wheels would end up spinning infinitely fast before the plane left the ground. In reality it is not possible to build a treadmill to take off from, but in theory, the plan would take off anyway since it is not thrusting against the ground, but the air, which is not affected by the treadmill.

As Kev so aptly stated:

IF THE TREADMILL WAS GOING A MILLION TRILLION BAJILLION GAGILLION MILES PER NANOSECOND IN THE OPPOSITE DIRECTION THE PLANE WOULD STILL FVCKING TAKE OFF.

 

[smack Down]

Originally posted by: Fraggable
Look man according to the wording of the question, the wheels would end up spinning infinitely fast before the plane left the ground. In reality it is not possible to build a treadmill to take off from, but in theory, the plan would take off anyway since it is not thrusting against the ground, but the air, which is not affected by the treadmill.

As Kev so aptly stated:

IF THE TREADMILL WAS GOING A MILLION TRILLION BAJILLION GAGILLION MILES PER NANOSECOND IN THE OPPOSITE DIRECTION THE PLANE WOULD STILL FVCKING TAKE OFF.

Where a force is applied makes no difference.

 

[Cerpin Taxt]

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

 

[MasonLuke]

i thought you kids would eventually see it my way.

i forgive those who cursed me and no need to pm an apolody

 

[Cerpin Taxt]

Originally posted by: Fraggable
Look man according to the wording of the question, the wheels would end up spinning infinitely fast before the plane left the ground.

This is a misunderstanding of the wording of the problem. As given, the treadmill matches the ground speed of the plane, not the rotational speed of the wheels. The latter isn't a coherent idea since the reverse movement of the treadmill directly affects the rotational speed of the wheels.

 

[MasonLuke]

Originally posted by: Garth

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

In the real world, the wheels would lock or skid or something, but within this thread regarding this hypothetical magical treadmill, wheels dont lock nor skid, it moves in the perfect opposite direction.

 

[smack Down]

Originally posted by: Garth

Originally posted by: Fraggable
Look man according to the wording of the question, the wheels would end up spinning infinitely fast before the plane left the ground.

This is a misunderstanding of the wording of the problem. As given, the treadmill matches the ground speed of the plane, not the rotational speed of the wheels. The latter isn't a coherent idea since the reverse movement of the treadmill directly affects the rotational speed of the wheels.

The later isn't incoherent. And is in fact how most people think about treadmill. A device that will keep the object on top of it is the same position. Most treadmill are really short because people stay in the same location.

 

[MasonLuke]

Originally posted by: Garth

Originally posted by: Fraggable
Look man according to the wording of the question, the wheels would end up spinning infinitely fast before the plane left the ground.

This is a misunderstanding of the wording of the problem. As given, the treadmill matches the ground speed of the plane, not the rotational speed of the wheels. The latter isn't a coherent idea since the reverse movement of the treadmill directly affects the rotational speed of the wheels.

i think it is clear that the treadmill matches the speed of the wheels. :beer:

 

[So]

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

In the real world, the wheels would lock or skid or something, but within this thread regarding this hypothetical magical treadmill, wheels dont lock nor skid, it moves in the perfect opposite direction.

If you are willing to concede that the wheels are to be treated as frictionless rollers, yet you still contend that the plane is stationary, then you are clearly ignorant of basic newtonian physics. A simple free body diagram solves this problem in a few seconds, and proves the plane takes off.

 

[MasonLuke]

wow after 700+ post, finally it was the ATOT forum that proved that the plane will not fly. Congratulations to all the kids who posted, you deserve a :beer:

now we can lay this to rest. Hip hip hurray!

 

[smack Down]

Originally posted by: So

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

In the real world, the wheels would lock or skid or something, but within this thread regarding this hypothetical magical treadmill, wheels dont lock nor skid, it moves in the perfect opposite direction.

If you are willing to concede that the wheels are to be treated as frictionless rollers, yet you still contend that the plane is stationary, then you are clearly ignorant of basic newtonian physics. A simple free body diagram solves this problem in a few seconds, and proves the plane takes off.

A free body diagram is worthless. You need to use equations of the system to see if the force applied via the treadmill is constant. I have no idea what equation to use to find that force but I don't think it is zero.

 

[JayMassive]

how can this be "teh stupidest myth EVER," as mentioned previously? this thread is quite lengthy, and people appear to still be divided about the truth of the matter...i'd say that's a pretty effective myth.

 

[MasonLuke]

hey kids, stop pming an apology im running out of space.

and yes, apology accepted.

 

[So]

Originally posted by: smack Down

Originally posted by: So

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

In the real world, the wheels would lock or skid or something, but within this thread regarding this hypothetical magical treadmill, wheels dont lock nor skid, it moves in the perfect opposite direction.

If you are willing to concede that the wheels are to be treated as frictionless rollers, yet you still contend that the plane is stationary, then you are clearly ignorant of basic newtonian physics. A simple free body diagram solves this problem in a few seconds, and proves the plane takes off.

A free body diagram is worthless. You need to use equations of the system to see if the force applied via the treadmill is constant. I have no idea what equation to use to find that force but I don't think it is zero.

He conceded that the wheels were frictionless bearings a FBD will do fine.

 

[JayMassive]

why in the hell would you assume the wheels are frictionless. if this is a myth, it has to remain in the real world, where friction is a fact of life, and necessary for most methods of travel...not that "real world" would mean much with a treadmill this large. i've never heard of a 747 on a cardio plan before...

 

[smack Down]

Originally posted by: So

Originally posted by: smack Down

Originally posted by: So

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

In the real world, the wheels would lock or skid or something, but within this thread regarding this hypothetical magical treadmill, wheels dont lock nor skid, it moves in the perfect opposite direction.

If you are willing to concede that the wheels are to be treated as frictionless rollers, yet you still contend that the plane is stationary, then you are clearly ignorant of basic newtonian physics. A simple free body diagram solves this problem in a few seconds, and proves the plane takes off.

A free body diagram is worthless. You need to use equations of the system to see if the force applied via the treadmill is constant. I have no idea what equation to use to find that force but I don't think it is zero.

He conceded that the wheels were frictionless bearings a FBD will do fine.

And friction isn't the only force. You can't make your free body diagram until you figure out the force involved and the equations for the forces. A FBD is really pointless because there are two force involved the force from the treadmill and the force from the jet and they are either equal or not equal.

 

[So]

Originally posted by: smack Down

Originally posted by: So

Originally posted by: smack Down

Originally posted by: So

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

In the real world, the wheels would lock or skid or something, but within this thread regarding this hypothetical magical treadmill, wheels dont lock nor skid, it moves in the perfect opposite direction.

If you are willing to concede that the wheels are to be treated as frictionless rollers, yet you still contend that the plane is stationary, then you are clearly ignorant of basic newtonian physics. A simple free body diagram solves this problem in a few seconds, and proves the plane takes off.

A free body diagram is worthless. You need to use equations of the system to see if the force applied via the treadmill is constant. I have no idea what equation to use to find that force but I don't think it is zero.

He conceded that the wheels were frictionless bearings a FBD will do fine.

And friction isn't the only force. You can't make your free body diagram until you figure out the force involved and the equations for the forces. A FBD is really pointless because there are two force involved the force from the treadmill and the force from the jet and they are either equal or not equal.

If the wheels are frictionless, there is only one force from the wheels. A constant upward force (Y direction) and no force transmitted in the X. Therefore the only forces acting on the plane are the engines and wheels counteracting gravity.

 

[So]

Originally posted by: JayMassive
why in the hell would you assume the wheels are frictionless. if this is a myth, it has to remain in the real world, where friction is a fact of life, and necessary for most methods of travel.

Friction is negligible, especially since it would be more of a limiting factor in the treadmill than in the plane, we can assume that the treadmill's bearings have enough friction that it can't move fast enough for the plane's wheel bearing friction to be a factor.

Think about this: aircraft are going extremely fast on takeoff and the bearing don't slow down the plane much. Does the plane lurch forward when it clears the ground? No, so one can conclude that the force is small.

 

[Cerpin Taxt]

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: MasonLuke
the ONLY way the plane will move forward is by the wheels turning. Yes or NO. the answer is yes.

NO. The plane could drag the wheels along if they were locked, and it would still move forward.

In the real world, the wheels would lock or skid or something, but within this thread regarding this hypothetical magical treadmill, wheels dont lock nor skid, it moves in the perfect opposite direction.

That doesn't change the fact that your claim "the ONLY way the plane will move forward is by the wheels turning" is false for the reasons given.

 

[Cerpin Taxt]

Originally posted by: smack Down

Originally posted by: Garth

Originally posted by: Fraggable
Look man according to the wording of the question, the wheels would end up spinning infinitely fast before the plane left the ground.

This is a misunderstanding of the wording of the problem. As given, the treadmill matches the ground speed of the plane, not the rotational speed of the wheels. The latter isn't a coherent idea since the reverse movement of the treadmill directly affects the rotational speed of the wheels.

The later isn't incoherent.

Yes it is. If the wheels roll +1 ft, then the tread mill will move -1 ft. Yet, because of the contact of the wheel with the treadmill, the wheel would have to move a net 2 ft as the reverse motion of the treadmill moves the wheel. Contradiction.

And is in fact how most people think about treadmill. A device that will keep the object on top of it is the same position. Most treadmill are really short because people stay in the same location.

That's not how I think of a treadmill. Maybe that's why I don't have the apparent mental block that yourself and MasonLuke do.

 

[Cerpin Taxt]

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: Fraggable
Look man according to the wording of the question, the wheels would end up spinning infinitely fast before the plane left the ground.

This is a misunderstanding of the wording of the problem. As given, the treadmill matches the ground speed of the plane, not the rotational speed of the wheels. The latter isn't a coherent idea since the reverse movement of the treadmill directly affects the rotational speed of the wheels.

i think it is clear that the treadmill matches the speed of the wheels. :beer:

Find me an original formulation of the problem which stipulates that. Then see above for an explanation of why it is incoherent.

 

[MasonLuke]

Originally posted by: JayMassive
why in the hell would you assume the wheels are frictionless. if this is a myth, it has to remain in the real world, where friction is a fact of life, and necessary for most methods of travel...not that "real world" would mean much with a treadmill this large. i've never heard of a 747 on a cardio plan before...

You ever seen a plane on a treadmill?
Is there a treadmill that can move in the EXACT opposite direction of wheels on a plane?

NO.

Kids, lesson #2, this is a hypothetical question and not a real world situation. you will NEVER see a plane on a treadmill that can counter the planes wheels percisely in the real world, let alone a plane on a treadmill.

Good day kids.

 

[PottedMeat]

Dammit isn't there any way to tank this thread?

Der Führer Adolf Hitler and Nazi Germany say the plane WILL NOT take off!

 

[MasonLuke]

This is the actual question, i did not write this:


?Imagine a plane is sitting on a massive conveyor belt, as wide and as long as a runway. The conveyer belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?"



Designed to EXACTLY match the speed of the wheels = no friction.

Kids, be proud of yourselves, you and all the ATOT crew PROVED the plane wont fly.


/thread

 

[JayMassive]

Originally posted by: MasonLuke

Originally posted by: JayMassive
why in the hell would you assume the wheels are frictionless. if this is a myth, it has to remain in the real world, where friction is a fact of life, and necessary for most methods of travel...not that "real world" would mean much with a treadmill this large. i've never heard of a 747 on a cardio plan before...

You ever seen a plane on a treadmill?
Is there a treadmill that can move in the EXACT opposite direction of wheels on a plane?

NO.

Kids, lesson #2, this is a hypothetical question and not a real world situation. you will NEVER see a plane on a treadmill that can counter the planes wheels percisely in the real world, let alone a plane on a treadmill.

Good day kids.

okay, now you're missing a point. if they're gonna test this, then real world does apply. obviously, and thank you for taking time out of your genius day to point this ouit, there won't be too many planes found on too many treadmills in the near future.

i take that back...this point isn't too clear for me. could you explain to me why i will "NEVER see a plane on a treadmill that can counter the planes wheels percisely in the real world, let alone a plane on a treadmill"...