Hi quickshift,
I asked about this and no one answered (I didn't see a response anyway). I seems to me the belt moves to stop the wheel from rotating.
-Chris
I asked about this and no one answered (I didn't see a response anyway). I seems to me the belt moves to stop the wheel from rotating.
-Chris
<<edit - hello 🙂 sorry - I can't type that fast 😀>>
If the wheels as a whole are doing 10 MPH, so it the belt. if the wheels rotate counter clockwise* the belt rotates clockwise.
* who imagines the wheels rotating clockwise and who imagines the wheels rotating counter clockwise?
Just interested🙂
BTW - if you think you are having a bad time with this... I have been thinking about it for a week longer <<sobs>>
anatech said:
If the wheels as a whole are doing 10 MPH, so it the belt. if the wheels rotate counter clockwise* the belt rotates clockwise.
* who imagines the wheels rotating clockwise and who imagines the wheels rotating counter clockwise?
Just interested🙂
BTW - if you think you are having a bad time with this... I have been thinking about it for a week longer <<sobs>>
eVITAERC said:
Think of this as a warm up, an apitiser if you will 🙂
Grad school will be soooo much worse
MHAHAHAHAHAHAHAHAHAHA
[/Dr Evil]
😉 😀
Hi quickshift,
The way I figure it, you have to think of linear motion (it's easier and everyone seems to be doing that). If the belt moves in the opposite direction, the wheel stops moving (rotating). So the wheel never rotates and never gets to even 10KPH.
But, the plane is forced forward and the belt can move. If the belt instantly keeps the same speed as the wheel, referenced to the wheel, it can move with respect to the ground. This satisfies all the requirements and nothing blows up.
-Chris
The way I figure it, you have to think of linear motion (it's easier and everyone seems to be doing that). If the belt moves in the opposite direction, the wheel stops moving (rotating). So the wheel never rotates and never gets to even 10KPH.
But, the plane is forced forward and the belt can move. If the belt instantly keeps the same speed as the wheel, referenced to the wheel, it can move with respect to the ground. This satisfies all the requirements and nothing blows up.
-Chris
Lo,
That's exactly what I think happens. Assuming the plane doesn't get taken out by a burning rollerblader or get covered in whale meat on the way down the belt. 😀
That's exactly what I think happens. Assuming the plane doesn't get taken out by a burning rollerblader or get covered in whale meat on the way down the belt. 😀
anatech said:So quickshift,
How many members are now unresponsive on the other board?
-Chris
😀 there are factions on the other board trying to put a stop to the thread - it has gone to about 650 replies 😀
Most people agreed that the plane would take off.
Some other people, who have been thinking about it now say that it won't take off because the tyres explode or something like that.
Some other people have just joined in and sent the arguement to page one again 😀
This bloke has been posting himself round in circles for the whole thread 😀
Hi quickshift,
Gee, you have all the fun! So they are crying uncle
on the other board.
We have a few that have confused themselves here too. Easy to do without limitations or explanations in the question. It's the religious zeal that I like watching.
See what a mess you made? Bettcha it was fun!
-Chris
Gee, you have all the fun! So they are crying uncle
on the other board.We have a few that have confused themselves here too. Easy to do without limitations or explanations in the question. It's the religious zeal that I like watching.
See what a mess you made? Bettcha it was fun!
-Chris
anatech said:
hehehe make that 2.4 on my recap post above 🙂 actually 2.3 was a general case of that one as I did say depending on which way the belt is turning.... that post was just an accumulation of ideas I had after thinking about the situation and all of the input from everyone else 🙂
I thought about that when you first posted it Chris, but I didn't understand what you meant until later, and by that time there had probably been another 50 posts 😉
Tony.
Hi Tony,
Don't feel bad. I woke up to a ton of new posts this morning too.
But you know what they say? "A snowflake in an avalanche never feels responsible" Sometimes I feel all alone, sigh.
-Chris
Don't feel bad. I woke up to a ton of new posts this morning too.
But you know what they say? "A snowflake in an avalanche never feels responsible" Sometimes I feel all alone, sigh.
-Chris
Well, the reason I had to switch camps last night was because for the wheel to make forward progress on the belt it has to move faster than the belt. Does anyone disagree with that?
Thrust, friction, etcetera simply don't enter into the picture. If the plane has moved from the beginning of the belt to the end, the wheels have miraculously moved faster than the belt.
Thrust, friction, etcetera simply don't enter into the picture. If the plane has moved from the beginning of the belt to the end, the wheels have miraculously moved faster than the belt.
Hi Chris,
at least this morning when I checked in (it's 9:34AM here) there are a lot fewer posts since I went to bed than yesterday 😉 the avalanche may be losing momentum!
Tony.
at least this morning when I checked in (it's 9:34AM here) there are a lot fewer posts since I went to bed than yesterday 😉 the avalanche may be losing momentum!
Tony.
Cal Weldon said:
If your refererence point for speed is a fixed point on the ground outside the belt (which is the norm) then yes I agree 🙂
edit: this was my original take on the question, however I got caught up trying to justify the belt would actually counteract the thrust of the engine which it can't... so the situation is in fact physically impossible.
Tony.
Hi Tony,
Now that's sad. It gives the server a work out.
Cal,
My belief is that the wheel does not turn. This makes the question reasonable within the framework of getting a real answer. The belt moves in relation to the earth to prevent the wheel from turning. The belt and wheel move at the same speed in relation to each other.
Hey, it's my universe. I can make my own rules! This answer has the benefit of allowing you to sleep at night.
Has anyone seen the poor skater withthe rocket tied on his back? I figure he will turn up as a Darwin at some point.
-Chris
Now that's sad. It gives the server a work out.
Cal,
My belief is that the wheel does not turn. This makes the question reasonable within the framework of getting a real answer. The belt moves in relation to the earth to prevent the wheel from turning. The belt and wheel move at the same speed in relation to each other.
Hey, it's my universe. I can make my own rules! This answer has the benefit of allowing you to sleep at night.
Has anyone seen the poor skater withthe rocket tied on his back? I figure he will turn up as a Darwin at some point.
-Chris
This borders on the insane. I've kept myself from working for over an hour while I read through this thread, and all I make of it is that unless we agree on a definition of the terms "speed" and "matches", we'll fail miserably. However, here's my take:
Suppose what we mean by speed is peripheral speed of tyre and belt, respectively. These two surfaces are tightly coupled via friction, and so must behave identically, and thus have matching speeds. If the plane is still the tyre is still and so is the belt. If the plane starts moving the tyre starts rolling around the axle along the belt. Since friction still applies and the belt is stationary, the peripheral speed of the tyre at the point of contact with the belt must also be stationary. Ergo, they match. Plane will take off. No matter how you vary the speed of the conveyor belt, the tyre will match, so tracking is essentially automatic. However, belt must move slightly for the directions of rotation to be opposite.
If "speed" means linear speed of wheel axle and peripheral speed of conveyor belt, there's no argument. Axle moves forward, belt moves backward, wheels spin faster. Wheels rotate in one direction, belt in the opposite. Plane flies.
If "speed" means angular velocity of wheels and belt tyres will go bust, unless the plane has really big wheels.
Another interesting thought experiment is this:
Suppose the plane is filled with helium or otherwise suspended in air such that the wheels just touch the conveyor belt. If we then postulate zero friction all around, what will happen if the belt starts moving, and nobody switched on the engines. My guess is the wheels will start spinning. How much force will the spinning excert on the plane? Not much... If we increase the speed of the belt? Still nothing? If the belt moves at infinite speed (angular or linear)? Still no force, right? What will then happen when the engines are switched on?
Know what? I bet the plane will move forward and take off.
Point is the only way the belt can stop the plane from flying is by defining "speed" as linear speed of wheel axle over the conveyor belt, and speed of the conveyor belt relative to ground. Then the plane will, by definition, be stationary relative to ground, but I'll be darned if I understand how that's supposed to happen!
Rune
Suppose what we mean by speed is peripheral speed of tyre and belt, respectively. These two surfaces are tightly coupled via friction, and so must behave identically, and thus have matching speeds. If the plane is still the tyre is still and so is the belt. If the plane starts moving the tyre starts rolling around the axle along the belt. Since friction still applies and the belt is stationary, the peripheral speed of the tyre at the point of contact with the belt must also be stationary. Ergo, they match. Plane will take off. No matter how you vary the speed of the conveyor belt, the tyre will match, so tracking is essentially automatic. However, belt must move slightly for the directions of rotation to be opposite.
If "speed" means linear speed of wheel axle and peripheral speed of conveyor belt, there's no argument. Axle moves forward, belt moves backward, wheels spin faster. Wheels rotate in one direction, belt in the opposite. Plane flies.
If "speed" means angular velocity of wheels and belt tyres will go bust, unless the plane has really big wheels.
Another interesting thought experiment is this:
Suppose the plane is filled with helium or otherwise suspended in air such that the wheels just touch the conveyor belt. If we then postulate zero friction all around, what will happen if the belt starts moving, and nobody switched on the engines. My guess is the wheels will start spinning. How much force will the spinning excert on the plane? Not much... If we increase the speed of the belt? Still nothing? If the belt moves at infinite speed (angular or linear)? Still no force, right? What will then happen when the engines are switched on?
Know what? I bet the plane will move forward and take off.
Point is the only way the belt can stop the plane from flying is by defining "speed" as linear speed of wheel axle over the conveyor belt, and speed of the conveyor belt relative to ground. Then the plane will, by definition, be stationary relative to ground, but I'll be darned if I understand how that's supposed to happen!
Rune
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