Earth spinning

in what way does it not make sense?, its direct substitution for one method of thrust / propulsion for another, neither of which is acting relative to the ground (which is key here). The fact you don't understand it doesn't make it incorrect.

Try it yourself, get some roller skates and a rope and take yourself off to the gym
 
Nate--IRL-- said:
The question still hasn't been defined, so..... 42

Nate
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Okay, I'll define the question.

A plane is on a treadmill, the treadmill is turned on at a fixed speed, the plane then turns on its engines, will it take off?

Edit - The engines are at normal take off power, as they would be when a plane is trying to take off.
 
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What more do I need to say?

Edit - I'm not trying to explain the original question, I'm posing the usual one, the one that doesn't make the question impossible.
 
youve turned on the planes engines, are they at idle ? Just on or ramped upto normal taxi levels ?
 
I really wish i had access to a tension Link Scale, I have a treadmill at home and some free spinning trolley wheels and some bricks and there's a relatively easy way of showing that the energy needed to pull/push a load on free spinning wheels on a treadmill is the same regardless of the treadmill being on or off.
 
LOAM said:
think of it like this, imagine a winch located at the end of the long treadmill but not on it, the winch rope is tied to the front of the jet, the treadmill is started and the winch are started at the same speed at the same time (the treadmill can at all times match the winch speed).
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That's completely defeated the purpose of the question! The winch would need to be on the treadmill to actually be part of a useful argument.

DAnDan said:
Okay, I'll define the question.

A plane is on a treadmill, the treadmill is turned on at a fixed speed, the plane then turns on its engines, will it take off?

Edit - The engines are at normal take off power, as they would be when a plane is trying to take off.
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The plane will take off in this instance, in the question that has been argued back and forth the plane won't take off.
 
How can people still be debating this?

In the 'normal' question the plane clearly takes off.

In the question in this thread, the statements made effectively mean that the plane's engines are unable to provide enough power to overcome the force exerted by the conveyor. It may not be realistic, but it certainly doesn't break any Laws of Physics. It just means that the plane has very weak engines. An unrealistic situation but not one which should be hard to comprehend from a problem solving point of view.



/exits thread and remembers again why you shouldn't start posting in these topics
 
for that to be the case though the engines would have to have been so weak as to not be able to move the plane at all, regardless of the treadmill. Which makes the whole thing moot anway.
 
LOAM said:
for that to be the case though the engines would have to have been so weak as to not be able to move the plane at all, regardless of the treadmill. Which makes the whole thing moot anway.
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No, it makes it a question in understanding forces, just like the original version of the question.

Just that in this example, you have to make the realisation that the statements made are effectively telling you that the engines can't accelerate the plane, and so it CAN'T take off!

Whereas in the 'normal' version, there is no such restriction and the realisation you make is that even though the treadmill keeps accelerating to match the PLANE'S speed, it doesn't matter, as the ENGINES are the driving force and the WHEELS are just a transfer point.

This is the point I made a long time ago. If you don't understand why this version is so completely different, then I don't believe you understand the original version as well as you think you do.
 
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