Plane

[RichA]

Imagine you and your mate are sat on one of the old fashioned roundabouts you used to get in playgrounds, you sit as close to the centre as you can, while he is sat on the outside edge. You are both rotating at the same rate, but he is travelling much faster than you.

I know, but nobody measures the speed of a wheel judged from a rotating point close to the centre. You measure it from the edge. And the RPM would be the same.

Number of revolutions in a time period. For example RPM - revolutions per minute?

Speed that a point on the rim of a wheel is doing in a tangential direction.

These are two different things as far as I can tell.

RPM is a measure of frequency of rotations, not speed.
For a wheel it only becomes speed when multiplied by the circumference of the wheel.
I don't see how anyone could say that the speed of a conveyor belt is the same as the RPM of the wheel that's rotating on it.
Unless the total length of the belt is the same as the circumference of the wheel. In which case the answer is no, the plane can't take off

 

[Voyager EMH]

I know, but nobody measures the speed of a wheel judged from a rotating point close to the centre. You measure it from the edge. And the RPM would be the same.


RPM is a measure of frequency of rotations, not speed.
For a wheel it only becomes speed when multiplied by the circumference of the wheel.
I don't see how anyone could say that the speed of a conveyor belt is the same as the RPM of the wheel that's rotating on it.
Unless the total length of the belt is the same as the circumference of the wheel. In which case the answer is no, the plane can't take off

Neither can I.
I leave rotational speed, RPM, out of it, for the conveyor and for the wheel.

For me, the tangential speed of the wheel is matches the speed of the conveyor.

 

[RichA]

Neither can I.
I leave rotational speed, RPM, out of it, for the conveyor and for the wheel.

For me, the tangential speed of the wheel is matches the speed of the conveyor.

So if wheels are at 150mph forwards and conveyor is at 150mph backwards, plane has 0 airspeed.

If wheels are at 0mph and conveyor is at 150mph backwards, plane has -150mph airspeed (purely for illustrative purposes).

If wheels are at 300mph forwards and conveyor is at 150mph backwards, plane has 150mph airspeed but "match the speed" rule is broken.

So 150mph airspeed with "match the speed" compliance requires the wheels to be rotating very fast but skidding forwards on the surface of the conveyor.

I don't feel like we've made any progress.

 

[Deleted member 35927]

So if wheels are at 150mph forwards and conveyor is at 150mph backwards, plane has 0 airspeed.

If wheels are at 0mph and conveyor is at 150mph backwards, plane has -150mph airspeed (purely for illustrative purposes).

If wheels are at 300mph forwards and conveyor is at 150mph backwards, plane has 150mph airspeed but "match the speed" rule is broken.

So 150mph airspeed with "match the speed" compliance requires the wheels to be rotating very fast but skidding forwards on the surface of the conveyor.

I don't feel like we've made any progress.

The problem lies in that youre trying to prove a fictional outcome as fact. It's just not the way it would work, so we can't agree with it.

 

[Whereditgo]

So if wheels are at 150mph forwards and conveyor is at 150mph backwards, plane has 0 airspeed.

If wheels are at 0mph and conveyor is at 150mph backwards, plane has -150mph airspeed (purely for illustrative purposes).

If wheels are at 300mph forwards and conveyor is at 150mph backwards, plane has 150mph airspeed but "match the speed" rule is broken.

So 150mph airspeed with "match the speed" compliance requires the wheels to be rotating very fast but skidding forwards on the surface of the conveyor.

I don't feel like we've made any progress.

That's the whole point of the OP.

 

[RichA]

The problem lies in that youre trying to prove a fictional outcome as fact. It's just not the way it would work, so we can't agree with it.

Which begs the question: why did you post the fictional problem in the first place and spend so long attempting to convince people that you had solved the simple problem as fact?

 

[Swango1980]

Which begs the question: why did you post the fictional problem in the first place and spend so long attempting to convince people that you had solved the simple problem as fact?

I think the OP could just be simplified.

If a plane tried to take off, but was on a giant treadmill operating at same speed plane wants to go, but in opposite direction, could the plane take off?

The answer would then just be yes, it could, just as normal.

We then would need to worry about wheel speed, rotation, etc

 

[Deleted member 35927]

Which begs the question: why did you post the fictional problem in the first place and spend so long attempting to convince people that you had solved the simple problem as fact?

No you specifically are. The premise of the op is plane on a conveyor and will it take off, that you chose to interpret it in a very specific way and spend days trying to prove it is up to you.

 

[Deleted member 35927]

I think the OP could just be simplified.

If a plane tried to take off, but was on a giant treadmill operating at same speed plane wants to go, but in opposite direction, could the plane take off?

The answer would then just be yes, it could, just as normal.

We then would need to worry about wheel speed, rotation, etc

Yes thats what I read it as. Sure I can go down a rabbit hole of nonsense but that's just stupid.

 

[RichA]

Yes thats what I read it as. Sure I can go down a rabbit hole of nonsense but that's just stupid.

Yet you keep coming back.
Like I said some time ago, it's more of a test of perception and interpretation than pure mechanics.
A couple of us choose to carry on spitballing for lols. If it upsets you, don't read it.
¯\_(ツ)_/¯

 

[Voyager EMH]

So if wheels are at 150mph forwards and conveyor is at 150mph backwards, plane has 0 airspeed.

If wheels are at 0mph and conveyor is at 150mph backwards, plane has -150mph airspeed (purely for illustrative purposes).

If wheels are at 300mph forwards and conveyor is at 150mph backwards, plane has 150mph airspeed but "match the speed" rule is broken.

So 150mph airspeed with "match the speed" compliance requires the wheels to be rotating very fast but skidding forwards on the surface of the conveyor.

I don't feel like we've made any progress.

Rule is never broken - as far as I am concerned.

"If wheels are at 300mph forwards and conveyor is at 150mph backwards", - can not happen.
The tangential speed of wheels must match the speed of conveyor.

In the time it takes for a wheel to make one rotation, the length of conveyor that has passed under the wheel is exactly one circumference of the wheel.
No skidding or slipping.

Those two lengths are the same. The time taken is the same. The speeds are the same.
Tangential speed of wheel matches speed of conveyor - where those two are in contact.

The top of the wheel has the same tangential speed as the bottom of the wheel - and the top of the wheel is in the opposite direction to the conveyor.

The above is easy to imagine occurring while the plane remains stationary on a moving conveyor.
But what happens when the plane moves forwards due to increase in power from the engines?

You have fixed thoughts that the wheels must rotate faster than the conveyor.
The wheels may be rotating faster than when the plane was stationary, but the conveyor passing beneath the wheels is doing so faster than before now that the plane is moving.
The same thing is happening, with regard to the wheel turning and the conveyor passing beneath it, but in a shorter time, because the plane is moving.
The result of this - the tangential speed of wheel matches the speed of conveyor - this happens because the wheels are passive.
The conveyor may be running at the same speed as before, but it is passing beneath the plane and beneath the wheels of the plane faster than before, because the plane is moving.
One circumference of the wheel will still turn across the same length of conveyor every time and in the same time-interval.

If the tangential speed of the wheel is greater than the conveyor speed, then this would mean the traction or grip was not happening and one turn of the wheel would contact more distance than the length of one circumference on the conveyor - slipping.

 

[Deleted member 35927]

Yet you keep coming back.
Like I said some time ago, it's more of a test of perception and interpretation than pure mechanics.
A couple of us choose to carry on spitballing for lols. If it upsets you, don't read it.
¯\_(ツ)_/¯

Yet you keep coming back.
Like I said some time ago, it's more of a test of perception and interpretation than pure mechanics.
A couple of us choose to carry on spitballing for lols. If it upsets you, don't read it.
¯\_(ツ)_/¯

Doesn't upset me I just don't get your point. You seem to have a fundamental misunderstanding of the forces involved and how they react with one another. To the point where youre using some unknown property to stop then plane

 

[Whereditgo]

I think the OP could just be simplified.

If a plane tried to take off, but was on a giant treadmill operating at same speed plane wants to go, but in opposite direction, could the plane take off?

The answer would then just be yes, it could, just as normal.

We then would need to worry about wheel speed, rotation, etc

The OP is worded with sufficient intentional ambiguity that people send themselves down rabbit holes of logic and confusion.

 

[Orikoru]

I think it would just about get off the ground an inch or two, so technically has 'taken off' but then it would immediately realise that it was stationary in mid-air and drop back to the ground again.

 

[Whereditgo]

Rule is never broken - as far as I am concerned.

"If wheels are at 300mph forwards and conveyor is at 150mph backwards", - can not happen.
The tangential speed of wheels must match the speed of conveyor.

In the time it takes for a wheel to make one rotation, the length of conveyor that has passed under the wheel is exactly one circumference of the wheel.
No skidding or slipping.

Those two lengths are the same. The time taken is the same. The speeds are the same.
Tangential speed of wheel matches speed of conveyor - where those two are in contact.

The top of the wheel has the same tangential speed as the bottom of the wheel - and the top of the wheel is in the opposite direction to the conveyor.

The above is easy to imagine occurring while the plane remains stationary on a moving conveyor.
But what happens when the plane moves forwards due to increase in power from the engines?

You have fixed thoughts that the wheels must rotate faster than the conveyor.
The wheels may be rotating faster than when the plane was stationary, but the conveyor passing beneath the wheels is doing so faster than before now that the plane is moving.
The same thing is happening, with regard to the wheel turning and the conveyor passing beneath it, but in a shorter time, because the plane is moving.
The result of this - the tangential speed of wheel matches the speed of conveyor - this happens because the wheels are passive.
The conveyor may be running at the same speed as before, but it is passing beneath the plane and beneath the wheels of the plane faster than before, because the plane is moving.
One circumference of the wheel will still turn across the same length of conveyor every time and in the same time-interval.

If the tangential speed of the wheel is greater than the conveyor speed, then this would mean the traction or grip was not happening and one turn of the wheel would contact more distance than the length of one circumference on the conveyor - slipping.

Not in the same time interval. As the wheel and conveyor increase speed the time for one circumference of travel will reduce.

The last line is what would happen with the conflicts of wheel speed being perfectly matched by the conveyor and the thrust of the engines.

 

[RichA]

Doesn't upset me I just don't get your point. You seem to have a fundamental misunderstanding of the forces involved and how they react with one another. To the point where youre using some unknown property to stop then plane

Velocity or speed = distance ÷ time
is neither rocket science or wizardry.
A positional change (distance) over a period of time without a change of speed would be wizardry. Unless the freewheel is also a teleportation device.
But as long as you can keep talking about Newton and reacting forces I'm reassured that you aren't taking the fantastical scenario of the mythical infinitely perfectly reactive conveyor belt too seriously.

The physicist described 3 ways of perceiving the puzzle. Yours and mine are clearly different.
Don't matter none.

 

[Bunkermagnet]

Since a gang of emiment and learned fellows were unable to come to a solid conclusion on this, I doubt very much that it can be solved on here regardless of who or what is shouting.
It cannot be proved either way, so will remain an inponderable.

 

[Deleted member 35927]

Since a gang of emiment and learned fellows were unable to come to a solid conclusion on this, I doubt very much that it can be solved on here regardless of who or what is shouting.
It cannot be proved either way, so will remain an inponderable.

Easily provable, just 1 or 2 have gone off on a strange tangent.

 

[Voyager EMH]

Not in the same time interval. As the wheel and conveyor increase speed the time for one circumference of travel will reduce.

The last line is what would happen with the conflicts of wheel speed being perfectly matched by the conveyor and the thrust of the engines.

You misunderstood me, or didn't read what I wrote very well. I said the same as this.

Comparing: plane moving and plane stationary.
I said that when plane is moving, one rotation of wheel is done over same length of conveyor, but this happens in a shorter time than when plane is stationary.

The one wheel turn and the coinciding circumference length of conveyor are done in the same time interval - always matching each other - the tangential speed of wheel matching speed of conveyor as the OP states.

I really do not understand how someone perceives one turn of wheel's circumference coming into contact with more than the length of its circumference of the surface it is contact with.
For me this always has to be the same, unless there is some slipping or skidding.

For the point of contact there are matched speeds: tangential speed of wheel - speed of conveyor.
If the speeds were different, one would have to be slipping over the other.

 

[RichA]

I really do not understand how someone perceives one turn of wheel's circumference coming into contact with more than the length of its circumference of the surface it is contact with.
For me this always has to be the same, unless there is some slipping or skidding.

For the point of contact there are matched speeds: tangential speed of wheel - speed of conveyor.
If the speeds were different, one would have to be slipping over the other.

Are you twisting my melon?
This is what I have been saying for some time.