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A question of physics.....

a simple little question, or is it?

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WolstonFlyer14/10/2016 00:18:04
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Opposite to the rotation of the wheels Stuart, if the plane wheels are turning anti-clockwise then the rollers on the conveyor are turning clockwise.

Still having fun?

@ Martin McIntosh- No I didn't fly the Tucano yet, it is almost finished and then I went and changed jobs and some other stuff that has pulled me away from building models for a while. But it will get finished!

Stuart C14/10/2016 00:27:15
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Yes, exactly. So it does take off as normal, but with static wheel rotation.

ted hughes14/10/2016 00:28:08
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It is a logic puzzle, which is not respectful of common sense or physics.

One of the earliest was Aeschylus and the tortoise.

The tortoise was given a 100m start in a race.

By the time Aeschylus had reached 100m, the tortoise had moved on.

When he reached that new point, the tortoise had moved on again, and so on ad finitum. So he never can overtake the tortoise.

We know it cannot be really possible, but that is the logical solution.

The plane cannot take off because it remains stationary.

ted hughes14/10/2016 00:29:55
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Posted by WolstonFlyer on 14/10/2016 00:18:04:

Opposite to the rotation of the wheels Stuart, if the plane wheels are turning anti-clockwise then the rollers on the conveyor are turning clockwise.

Still having fun?

@ Martin McIntosh- No I didn't fly the Tucano yet, it is almost finished and then I went and changed jobs and some other stuff that has pulled me away from building models for a while. But it will get finished!

The wheels are turning as per normal for forward speed.

You'll never get it, will you?

It is a logic puzzle.

WolstonFlyer14/10/2016 00:33:57
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Posted by ted hughes on 14/10/2016 00:29:55:

You'll never get it, will you?

It is a logic puzzle.

Me ted?

I get it, I started the thread.

Of course it is a puzzle, that's why I posted it, lots of interesting comments so far. My mobile phone has been going crazy with the emails all day

Edited By WolstonFlyer on 14/10/2016 00:34:28

ted hughes14/10/2016 00:37:49
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Posted by WolstonFlyer on 14/10/2016 00:33:57:
Posted by ted hughes on 14/10/2016 00:29:55:

You'll never get it, will you?

It is a logic puzzle.

Me ted?

I get it, I started the thread.

Of course it is a puzzle, that's why I posted it, lots of interesting comments so far. My mobile phone has been going crazy with the emails all day

Edited By WolstonFlyer on 14/10/2016 00:34:28

Fun thread, I enjoy it!

WolstonFlyer14/10/2016 00:39:40
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Posted by ted hughes on 14/10/2016 00:37:49:
Fun thread, I enjoy it!

Good, that was the idea yes smiley

Gary Manuel14/10/2016 00:50:41
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Posted by ted hughes on 14/10/2016 00:37:49:
Posted by WolstonFlyer on 14/10/2016 00:33:57:
Posted by ted hughes on 14/10/2016 00:29:55:

You'll never get it, will you?

It is a logic puzzle.

Me ted?

I get it, I started the thread.

Of course it is a puzzle, that's why I posted it, lots of interesting comments so far. My mobile phone has been going crazy with the emails all day

Edited By WolstonFlyer on 14/10/2016 00:34:28

Fun thread, I enjoy it!

Shame you didn't manage to solve the puzzle devil

Stuart C14/10/2016 00:55:42
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"Opposite to the rotation of the wheels Stuart, if the plane wheels are turning anti-clockwise then the rollers on the conveyor are turning clockwise." - No they aren't.

ted hughes14/10/2016 00:57:18
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Gary, when the plane provides thrust, its wheels will turn.

The conveyor belt matches the speed of  that turn.

The plane remains stationary.

It can't fly.

It is a logic puzzle, not a physical one.

I give up on this.

Edited By ted hughes on 14/10/2016 00:59:02

ted hughes14/10/2016 00:58:24
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It has been fun, but I give up.

It is a question of logic, not common sense or physics.

Stuart C14/10/2016 01:08:33
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Garry's first post was correct. All else has been mind boggling fun. smiley

ted hughes14/10/2016 01:13:54
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Posted by Gary Manuel on 12/10/2016 21:12:31:

Yes - as long as the conveyor is long enough.

The 747 is driven forwards by the jet engines, not the wheels.

The wheels / conveyor might be turning, but that is irrelevant.

As long as the conveyor is long enough?

Not university educated, I hazard a guess?

Gary Manuel14/10/2016 01:17:49
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It's a question of logic, common sense and physics.

Here's a clue.

What is the speed of the wheel?

Bare in mind that the wheel is firmly attached to the plane - whether or not it is rotating has nothing to do with it's speed.

Think about how fast the wheels on your car are travelling when you are driving at 70mph. They manage to keep up with you, so they must also be doing 70mph.

You can also spin a wheel as fast as you like in your hands, but the wheel has no speed - it's just spinning on a stationary axis.

ted hughes14/10/2016 01:20:02
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Posted by Gary Manuel on 14/10/2016 01:17:49:

It's a question of logic, common sense and physics.

Here's a clue.

What is the speed of the wheel?

Bare in mind that the wheel is firmly attached to the plane - whether or not it is rotating has nothing to do with it's speed.

Think about how fast the wheels on your car are travelling when you are driving at 70mph. They manage to keep up with you, so they must also be doing 70mph.

You can also spin a wheel as fast as you like in your hands, but the wheel has no speed - it's just spinning on a stationary axis.

It is a logic puzzle.

The speed of any wheel is irrelevant

Do'h!

Gary Manuel14/10/2016 01:20:14
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Posted by ted hughes on 14/10/2016 01:13:54:
Posted by Gary Manuel on 12/10/2016 21:12:31:

Yes - as long as the conveyor is long enough.

The 747 is driven forwards by the jet engines, not the wheels.

The wheels / conveyor might be turning, but that is irrelevant.

As long as the conveyor is long enough?

Not university educated, I hazard a guess?

School of life.

WolstonFlyer14/10/2016 01:20:20
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This guy gives it a good attempt but forgets that the conveyor belt will increase its speed at the same time that he increases the speed of the aircraft, as it says in the text of the question, "the belt is designed to exactly match the speed of the wheels moving in the opposite direction".

In this video the speed of the belt is constant when it finally gets to its top speed, so does not match the speed of the wheels when the plane accelerates further, so the plane can move forwards and potentially take off.

If the running machine could continue to increase its speed the plane would not be able to accelerate further in order to move forwards and gain air speed.

So not a correct demonstration of the question but a good effort!

 

Edited By WolstonFlyer on 14/10/2016 01:26:25

Edited By WolstonFlyer on 14/10/2016 01:27:38

ted hughes14/10/2016 01:21:02
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Gary, stop now, you are embarrassing yourself.

Gary Manuel14/10/2016 01:24:02
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OK Ted. Whatever you say.

WolstonFlyer14/10/2016 01:32:21
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Don't get grumpy chaps, watch the video I posted above.

It is not quite correct as the explanation in the text says, because the running machine cannot go fast enough to match the speed of the rotation of the wheels.

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