Earth spinning

["andy"]

As the only way this can occur, is if there is zero forward movement on the plane (in relation to the ground - assuming the treadmill is fixed to the ground).

no its not the treadmill can spin twice the speed of those wheels if it wants but it still aint stopping the plane thats not connected (except by tiny amounts of bearing friction) to the wheels going forwards through the air and taking off

 

[div0]

Thank you.

No problem, I wouldn't have posted, but it astounds me at the amount of people who don't understand the point you're making.

Some people may argue that it is semantics, some may have just missed that the question is phrased differently from the 'normal' version. Bot for a forum of people with a mainly science-based background, I'd have expected the change in wording of the question to have instantly jumped out and slapped them in the face that the answer to this question was different to normal!!

 

[neodude]

no its not

So enlighten me. How when the treadmill is matching the speed of the wheels can the plane move anywhere? without skidding?

 

[div0]

no its not

Yes it is. Read the question. The speed of the treadmill and the speed of the WHEELS are equal and opposite. Not the speed of the treadmill and the speed of the PLANE!

It is a totally different question from the 'normal' version.

How can people miss the difference?

 

[Nate--IRL--]

Like how?

Like calculations of force imparted from this bearing?

You are basically saying that the wheel will turn with such speed, induce such friction in the bearing, that it will impart a force to the wheel struts that will counteract the 63,300lbs of thrust from the engines? Not to mention without ripping the wheel struts from the plane?

Edit:- It's power is relative to the air it can move through the engines, this is unaffected by the wheels

Nate

 

[neodude]

Like calculations of force imparted from this bearing?

You are basically saying that the wheel will turn with such speed, induce such friction in the bearing, that it will impart a force to the wheel struts that will counteract the 63,300lbs of thrust from the engines? Not to mention without ripping the wheel struts from the plane?

Edit:- It's power is relative to the air it can move through the engines, this is unaffected by the wheels

Nate

I didn't say it wouldn't rip out the strut. In fact I stated that the wheels would probably melt/explode. The fact remains that in this situation the plane ain't going anywhere.

 

[div0]

Like calculations of force imparted from this bearing?

You are basically saying that the wheel will turn with such speed, induce such friction in the bearing, that it will impart a force to the wheel struts that will counteract the 63,300lbs of thrust from the engines? Not to mention without ripping the wheel struts from the plane?



Nate

This is irrelevant.

The question is phrased such that the treadmill is moving at equal speed to the WHEELS (not to the PLANE).

It doesn't matter how impractical you argue this is. The simple fact is, that the question is telling you the plane's engines are unable to apply sufficient force to move the plane forwards (in relation to the ground).

You cannot argue against that.

The question may not be realistic, but Neodude is fundamentally correct and anyone that keeps arguing against this is hugely missing the point. And imo, if you understood the 'normal' question as well as you think you do, then you'd understand why this difference in the wording is so crucially important.

 

[Dano]

No problem, I wouldn't have posted, but it astounds me at the amount of people who don't understand the point you're making.

That he can choose when to turn off the laws of physics to try and prove his point as and when needed, I think most of us have got it

Some people may argue that it is semantics, some may have just missed that the question is phrased differently from the 'normal' version. Bot for a forum of people with a mainly science-based background, I'd have expected the change in wording of the question to have instantly jumped out and slapped them in the face that the answer to this question was different to normal!!

It's not different to normal, it's flawed and using fantasy physics means anything could be true and thus nothing is true, get the point yet? Either the laws of physics apply in which case it'll take off or they don't and it can do whatever the hell anybody cares to think of including turning into a bright pink four hundred storey elephant with a penchant for flip flops.

 

[neodude]

It's not different to normal, it's flawed and using fantasy physics means anything could be true and thus nothing is true, get the point yet? Either the laws of physics apply in which case it'll take off or they don't and it can do whatever the hell anybody cares to think of including turning into a bright pink four hundred storey elephant with a penchant for flip flops.

I didn't make the question up. The question by its nature suggests a magical treadmill that can instantly match any speed.

 

["andy"]

That he can choose when to turn off the laws of physics to try and prove his point as and when needed, I think most of us have got it



It's not different to normal, it's flawed and using fantasy physics means anything could be true and thus nothing is true, get the point yet? Either the laws of physics apply in which case it'll take off or they don't and it can do whatever the hell anybody cares to think of including turning into a bright pink four hundred storey elephant with a penchant for flip flops.

exactly. and when neodude is making comments about weight/speed effecting the bearings and heavy cars needing big engines to combat this bearing friction then its hard to ever believe he ever knew what was happening

 

[Nate--IRL--]

This is irrelevant.

The question is phrased such that the treadmill is moving at equal speed to the WHEELS (not to the PLANE).

As long as the wheel doesn't skid this will always be the case, the wheel will rotate on the track at matching, equal and opposite, speeds. You have neglected to give a frame of reference. Is this relative to the ground, the treadmill, the treadmill track, the wheel strut, the air?

Nate

 

[neodude]

As long as the wheel doesn't skid this will always be the case, the wheel will rotate on the track at matching, equal and opposite, speeds. You have neglected to give a frame of reference. Is this relative to the ground, the treadmill, the treadmill track, the wheel strut, the air?

Nate

The rotational speed of the wheel. As most people would assume by the phrase wheelspeed. i.e. the speed of the outer surface of the tyre in reference to the centre of the axle.

 

[Nate--IRL--]

Grand,

Now explain to me the relationship between the wheel speed and the wheel strut. You are suggesting the bearing could impart 63,300lbs of force?

Nate

 

[neodude]

I'm suggesting that with the treadmill at sufficiently high speeds the force pushing back against the axle does increase. The force isn't caused by bearing friction (that is constant) but bearing friction is a factor of it. People are assuming that the rearwards movement of the belt is all used just to rotate the wheels, this is not true. A fraction of this movement is translated into a linear force which acts through the tyre onto the axle directly. At low speeds this is not noticeable but at extremely high speeds it does become a factor. The bearing resistance is a factor in how much this force increases with speed. Given a magical treadmill capable of infinite speeds then it would be possible to provide enough movement in the belt to balance the force of the engines.

But as stated above this is all a different argument. The fact is that for the plane to move without skidding the rules of the question are broken.

 

[Nate--IRL--]

I'm suggesting that with the treadmill at sufficiently high speeds the force pushing back against the axle does increase. The force isn't caused by bearing friction (that is constant) but bearing friction is a factor of it. People are assuming that the rearwards movement of the belt is all used just to rotate the wheels, this is not true. A fraction of this movement is translated into a linear force which acts through the tyre onto the axle directly. At low speeds this is not noticeable but at extremely high speeds it does become a factor. The bearing resistance is a factor in how much this force increases with speed. Given a magical treadmill capable of infinite speeds then it would be possible to provide enough movement in the belt to balance the force of the engines.

Well if this magical treadmill is using frictionless bearings in order to rotate, why can't the pane use the same bearing? It's already got super strength struts to get this far. And yes any rearward force is a vector of Bearing Friction alone. there is no other connection between the wheel and axle.

But as stated above this is all a different argument. The fact is that for the plane to move without skidding the rules of the question are broken.

No, the question is broken because it does not include a frame of reference.

Nate

 

[neodude]

No, the question is broken because it does not include a frame of reference.

I agree. There is no frame of reference. But the majority of normal people on hearing the term "wheelspeed" would assume that it is the rotational speed of the wheel in reference to the axle.

 

[DAnDan]

This thread is scary, some people really need to learn some physics before commenting.

Regardless of how fast the treadmill goes, the plane will take off. If the treadmill goes faster, the plane's speed will be UNCHANGED, the wheels will just spin faster.

That's it, nothing else to it.

 

[neodude]

This thread is scary, some people really need to learn some physics before commenting.

Regardless of how fast the treadmill goes, the plane will take off. If the treadmill goes faster, the plane's speed will be UNCHANGED, the wheels will just spin faster.

That's it, nothing else to it.

The wheels can't spin faster. The question states that the treadmill will match the speed of the wheels.

 

[Beren]

The treadmill cannot match the speed of the wheels while thrust is being applied by the engines, period. The question has been malformed and you are arguing semantics because somebody failed to type the question correctly and in doing so decided to break the laws of physics.

Holy cataclysmic event Batman! He asked a question that Broke the Laws Of Physics!

Sorry your semantics failed

Sorry couldn't help it - your quote belongs somewhere in the Hitch Hikers Guide along the lines of what happens when the Question and Answer appear simultaneaously.

 

[arknor]

put teflon coated ski's onto the plant, cover the treadmill in oil.

it will take off!

The wheels can't spin faster. The question states that the treadmill will match the speed of the wheels.

so the plane wont take off if the wheels are fixed speed?

what if its a VTOL PLANE with snakes onboard! HAH!