Skill's weekend teaser

What will happen?

  • The plane will take off normally

    Votes: 25 40.3%

  • The plane will remain stationary

    Votes: 32 51.6%

  • The plane will run out of conveyor belt before it can take off

    Votes: 5 8.1%
  • Total voters
    62
  • Poll closed .
Skill Leverage said:
Sigh...

If the engine is switched off, yes. If not, no.

Since you cannot get past this basic point, seriously, I am leaving.
Click to expand...
Don't go Skills - I don't want to win by default...

Either the coveyor is rigged to match the speed of the plane or it's not. Which is it? There was no mention of the engines mystically communicating their condition with either the wheels or the conveyor in your post #1.
 
OK, Bramble:

The conveyor belt merely causes the wheels to spin, frictionlessly, on their axels. The plane does not move in any way due to this. It only moves when the engine is switched on.

Say the belt is moving at a billion miles an hour. The wheels are, in turn, spinning at a billion miles an hour (rotational speed.)

THE NET FORCE ON THE PLANE IS ZERO - the wheels are spinning on their axes, the plane is not moving at all.

Now, the engines are switched on - THE NET FORCE ON THE PLANE BECOMES POSITIVE - the plane takes off!!!!
 
TheBramble said:
If the conveyor is set up to exactly match the speed of the plane's wheels, does that mean that regardless of the speed of the conveyor, the plane will not be moving relative to the ground upon which the conveyor sits? Is my analysis, so far, correct?
Click to expand...

The conveyor is spinning the wheels! They will always match.

Most people can push a car that is not in gear along a flat road, not very fast, but they can still move it. Now put the car on a conveyor and while standing on firm ground, push against the car when the conveyor is switched on at 10mph. The wheels move at 10mph but the car is going nowhere. Now, increase the speed to 20mph, 30mph, 40..50...even at 100mph the energy needed to push against the car to keep it stationary doesn't increase (assuming minimum wheel bearing friction). Now, push just a little harder and the car will move forward against the conveyor, even if the wheels and conveyor are moving at 500mph.
 
TheBramble said:
Don't go Skills - I don't want to win by default...

Either the coveyor is rigged to match the speed of the plane or it's not. Which is it? There was no mention of the engines mystically communicating their condition with either the wheels or the conveyor in your post #1.
Click to expand...


FFS!!!! This has to be a troll...

The engines don't communicate with the F*C*ING WHEELS, because the wheels don't affect the plane's forward motion!!!

LEARN TO READ!!! UNDERSTAND!!! COGITATE!!! AAAAAAAAAAAAAAAAARGH
 
new_trader said:
The conveyor is spinning the wheels! They will always match.

Most people can push a car that is not in gear along a flat road, not very fast, but they can still move it. Now put the car on a conveyor and while standing on firm ground, push against the car when the conveyor is switched on at 10mph. The wheels move at 10mph but the car is going nowhere. Now, increase the speed to 20mph, 30mph, 40..50...even at 100mph the energy needed to push against the car to keep it stationary doesn't increase (assuming minimum wheel bearing friction). Now, push just a little harder and the car will move forward against the conveyor, even if the wheels and conveyor are moving at 500mph.
Click to expand...

DO YOU SEE?! DO YOU SEE HOW PEOPLE ARE WRITING EXACTLY THE SAME STUFF AS ME AT THE SAME TIME IN RESPONSE TO YOUR POSTS?!?!?! HOW COULD THIS BE??!?!?!

I'll tell you why; WE UNDERSTAND THE PISSING PROBLEM
 
Skill Leverage said:
OK, Bramble:

The conveyor belt merely causes the wheels to spin, frictionlessly, on their axels. The plane does not move in any way due to this. It only moves when the engine is switched on.

Say the belt is moving at a billion miles an hour. The wheels are, in turn, spinning at a billion miles an hour (rotational speed.)

THE NET FORCE ON THE PLANE IS ZERO - the wheels are spinning on their axes, the plane is not moving at all.

Now, the engines are switched on - THE NET FORCE ON THE PLANE BECOMES POSITIVE - the plane takes off!!!!
Click to expand...
WHAT!!! This is not the detail in post #1. Which one are we solving for? The original one or this new one?
 
The key point, by the way, in new_trader's post is, the car is not in gear. This is exactly the same for these purposes as a plane whose wheels do not create forward motion.

Please get this through your bloody skull so I can go and cry in my pillow.
 
Fair enough I didn't mention that the wheels are frictionless, but it doesn't really matter; even if there were friction, the plane still takes off once it has overcome this! New_trader explained it perfectly.

Please tell me the penny has dropped and I can go...
 
Skill Leverage said:
Imagine a 747 sitting on a very large conveyor belt. The belt has the same dimensions as a runway at an airport*, and is set up to exactly match the speed of the plane's wheels, moving in the opposite direction.
Click to expand...
|So, let's pretned the wheels are merely used to determine the speed of the plane over the surface of the conveyor. If the conveyor is always moving at the same speed, but in an opposite direction to the wheels, regardless of the speed, the net forward motion of the plane relative to the ground upon which the conveyor is standing is 0 mph. Have I got that right?

If I have, where does the 180 mph breeze necessary to provide sufficient lift to loft the bastie upward come from?
 
Going to quote what I said in the previous teaser thread:

I'm eagerly awaiting the sh*tstorm that the "plane on a treadmill" will generate
Click to expand...

Skill Leverage is correct, the plane will take off. The reason people seem to struggle with this problem is that they assume that the moving conveyer belt is providing a force opposing the plane's foward movement. In reality, the force created by the conveyer belt only acts on the wheels, and since the wheels can move completely independently of the plane, the force from the conveyer belt doesn't affect the plane. Obviously this assumes the wheels can spin freely without friction - stick the brakes on and the conveyer belt will be able to exert a force on the plane as a whole.
 
TheBramble said:
|So, let's pretned the wheels are merely used to determine the speed of the plane over the surface of the conveyor. If the conveyor is always moving at the same speed, but in an opposite direction to the wheels, regardless of the speed, the net forward motion of the plane relative to the ground upon which the conveyor is standing is 0 mph. Have I got that right?

If I have, where does the 180 mph breeze necessary to provide sufficient lift to loft the bastie upward come from?
Click to expand...

FROM THE BLOODY ENGINE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
Skill Leverage said:
The key point, by the way, in new_trader's post is, the car is not in gear. This is exactly the same for these purposes as a plane whose wheels do not create forward motion.

Please get this through your bloody skull so I can go and cry in my pillow.
Click to expand...
Skills, I don't want to get side-tracked onto cars and stuff. I'm having a tough enough time trying to pin you down on what you really mean in post #1.
 
The Dirty Great Big Engines That Always Make A Plane Fly!!!!!!!!!!

Do You Understand Aoifhpsadfhu Sacfnisbwesuf@#hf@#jf@8
 
TheBramble said:
NO. Never flown multi-engine. I just 'treated myself' to a PPL 7 years ago and fly fairly regularly still. I reckon that puts me in the 5% most likely to at least be aware of the physical realities and practicalities of aerodynamic flight.
Click to expand...

Maybe so, but it does not put you in the 38(ish)% that actually understand the nature - and solution - to the problem.

What will it take to make you substitute your position (that it won't take off) with the correct one (that it will)? Will you claim you are correct until you see, at first hand, a 747 actually take off from a treadmill?

What is it about this that you don't understand?
 
TheBramble said:
|So, let's pretned the wheels are merely used to determine the speed of the plane over the surface of the conveyor. If the conveyor is always moving at the same speed, but in an opposite direction to the wheels, regardless of the speed, the net forward motion of the plane relative to the ground upon which the conveyor is standing is 0 mph. Have I got that right?

If I have, where does the 180 mph breeze necessary to provide sufficient lift to loft the bastie upward come from?
Click to expand...

Seriously, from the engine.

Game, set and match. This perfectly encapsulates, and answers, the problem. You lose.
 
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