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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:15:24

edit (double post)
Last edited by Chicken_Little on Tue 02 Jan 2007, 21:16:49, edited 1 time in total.
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Re: Ask me a question

Unread postby MD » Tue 02 Jan 2007, 21:15:50

Ignore the damn conveyor and wheels.

An aircraft thrusts against the air, not the ground. They conveyor can do whatever you want until you blow up the gear from overspeed, which is a completely different issue.
Last edited by MD on Tue 02 Jan 2007, 21:31:44, edited 1 time in total.
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:18:45

$this->bbcode_second_pass_quote('MD', 'I')gnore the damn conveyor and wheels.

An aircraft thrusts against the air, not the ground. They conveyor can do whatever you want until you blow up the gear from overspeed, which is a completely different issue.


incorrect. if aircraft engines needed to 'thrust against' anything then space flight would be impossible (newtonian physics 101)
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Re: Ask me a question

Unread postby davep » Tue 02 Jan 2007, 21:19:37

$this->bbcode_second_pass_quote('Chicken_Little', 'b')ut the plane doesn't move relative to the ground. it remains in exactly the same place. the conveyor belt moves but the plane doesn't.

say we plant a flag in the ground next to the starting position of the plane. the plane never passes the flag.


Untrue. You said:

$this->bbcode_second_pass_quote('', 'T')he conveyor belt is tuned such that it matches the speed of the aircraft whatever ground speed the aircraft attains.


Therefore, it matches the ground speed. So if the plane is travelling at 180mph <b> ground speed ffs!</b> so is the conveyor. The plane is not still.
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Re: Ask me a question

Unread postby davep » Tue 02 Jan 2007, 21:21:01

$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('MD', 'I')gnore the damn conveyor and wheels.

An aircraft thrusts against the air, not the ground. They conveyor can do whatever you want until you blow up the gear from overspeed, which is a completely different issue.


incorrect. if aircraft engines needed to 'thrust against' anything then space flight would be impossible (newtonian physics 101)


OK, he's trolling now
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:29:48

$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('Chicken_Little', 'b')ut the plane doesn't move relative to the ground. it remains in exactly the same place. the conveyor belt moves but the plane doesn't.

say we plant a flag in the ground next to the starting position of the plane. the plane never passes the flag.


Untrue. You said:

$this->bbcode_second_pass_quote('', 'T')he conveyor belt is tuned such that it matches the speed of the aircraft whatever ground speed the aircraft attains.


Therefore, it matches the ground speed. So if the plane is travelling at 180mph <b> ground speed ffs!</b> so is the conveyor. The plane is not still.


but we're only talking here about the ground speed the plane would have had had it not been on a moving conveyor belt. what i should have said there was 'notional ground speed'.

the actual literal ground speed of the plane in this exercise is obviously zero. sorry, i should have made that clearer.
Last edited by Chicken_Little on Tue 02 Jan 2007, 21:33:56, edited 1 time in total.
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:31:52

$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('MD', 'I')gnore the damn conveyor and wheels.

An aircraft thrusts against the air, not the ground. They conveyor can do whatever you want until you blow up the gear from overspeed, which is a completely different issue.


incorrect. if aircraft engines needed to 'thrust against' anything then space flight would be impossible (newtonian physics 101)


OK, he's trolling now


wrong. rocket engines do not need to 'thrust against' anything to work, nor do jet engines as long as they have an oxygen supply.

'every action has an equal and opposite reaction'.
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Re: Ask me a question

Unread postby MD » Tue 02 Jan 2007, 21:34:55

$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('MD', 'I')gnore the damn conveyor and wheels.

An aircraft thrusts against the air, not the ground. They conveyor can do whatever you want until you blow up the gear from overspeed, which is a completely different issue.


incorrect. if aircraft engines needed to 'thrust against' anything then space flight would be impossible (newtonian physics 101)


OK, he's trolling now


Or hopefully just speaking from ignorance. I'd hate to think the concept was unfathomable.
Stop filling dumpsters, as much as you possibly can, and everything will get better.

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Re: Ask me a question

Unread postby davep » Tue 02 Jan 2007, 21:36:54

$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('Chicken_Little', 'b')ut the plane doesn't move relative to the ground. it remains in exactly the same place. the conveyor belt moves but the plane doesn't.

say we plant a flag in the ground next to the starting position of the plane. the plane never passes the flag.


Untrue. You said:

$this->bbcode_second_pass_quote('', 'T')he conveyor belt is tuned such that it matches the speed of the aircraft whatever ground speed the aircraft attains.


Therefore, it matches the ground speed. So if the plane is travelling at 180mph <b> ground speed ffs!</b> so is the conveyor. The plane is not still.


but we're only talking here about the ground speed the plane would have had had it not been on a moving conveyor belt.

the actual literal ground speed of the plane in this exercise is obviously zero. sorry, i should have made that clearer.


That's a bit rubbish. So you're saying that the speed of the plane is relative to the conveyor belt in exact proportions, whereby ground speed equals zero? That's a stupid question frankly and would need far more info to be able to see if the plane can get enough tyre speed up to lose some of the friction and start making headway.
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:41:19

$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('Chicken_Little', 'b')ut the plane doesn't move relative to the ground. it remains in exactly the same place. the conveyor belt moves but the plane doesn't.

say we plant a flag in the ground next to the starting position of the plane. the plane never passes the flag.


Untrue. You said:

$this->bbcode_second_pass_quote('', 'T')he conveyor belt is tuned such that it matches the speed of the aircraft whatever ground speed the aircraft attains.


Therefore, it matches the ground speed. So if the plane is travelling at 180mph <b> ground speed ffs!</b> so is the conveyor. The plane is not still.


but we're only talking here about the ground speed the plane would have had had it not been on a moving conveyor belt.

the actual literal ground speed of the plane in this exercise is obviously zero. sorry, i should have made that clearer.


That's a bit rubbish. So you're saying that the speed of the plane is relative to the conveyor belt in exact proportions, whereby ground speed equals zero? That's a stupid question frankly and would need far more info to be able to see if the plane can get enough tyre speed up to lose some of the friction and start making headway.

the wheels of the plane are ideal wheels in the sense that they cause no friction relative to the conveyor belt. Nor is there any friction in the wheel bearings.
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Re: Ask me a question

Unread postby davep » Tue 02 Jan 2007, 21:42:21

OK, let's end this. It's a VTOL Harrier

<b> pwned! </b>
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:42:27

$this->bbcode_second_pass_quote('MD', '')$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('MD', 'I')gnore the damn conveyor and wheels.

An aircraft thrusts against the air, not the ground. They conveyor can do whatever you want until you blow up the gear from overspeed, which is a completely different issue.


incorrect. if aircraft engines needed to 'thrust against' anything then space flight would be impossible (newtonian physics 101)


OK, he's trolling now


Or hopefully just speaking from ignorance. I'd hate to think the concept was unfathomable.


sorry but i'm right, like it or not. look it up.
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:43:10

$this->bbcode_second_pass_quote('davep', 'O')K, let's end this. It's a VTOL Harrier

<b> pwned! </b>


no, it's a Boeing 747, as stated earlier.
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Re: Ask me a question

Unread postby PenultimateManStanding » Tue 02 Jan 2007, 21:44:27

I've got one that always puzzled me: how come if a twin goes up in space and flies at great speed relative to the earth and comes back a long time later, his twin on earth has aged more than him? isn't speed relative? if there is no absolute speed (except c which is the same in all reference frames) then wouldn't the twin on earth be speeding fast relative to the twin in the spaceship? I get the idea of time in a gravity well, but the relative speed thing always stumped me.
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Re: Ask me a question

Unread postby davep » Tue 02 Jan 2007, 21:48:13

$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('davep', 'O')K, let's end this. It's a VTOL Harrier

<b> pwned! </b>


no, it's a Boeing 747, as stated earlier.


Bugger.

OK, there is a certain amount of lift in the positioning of the engines...

Nah, I'm convinced that the thrust of the engines (coupled with the not quite horizontal positioning) means that the force and the reduced weight would enable some kind of decoupling. Unless there was something to actually brake it, the wheels would skid and the plane would advance anyway.
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:49:55

$this->bbcode_second_pass_quote('PenultimateManStanding', 'I')'ve got one that always puzzled me: how come if a twin goes up in space and flies at great speed relative to the earth and comes back a long time later, his twin on earth has aged more than him? isn't speed relative? if there is no absolute speed, then wouldn't the twin on earth be speeding fast relative to the twin in the spaceship? I get the idea of time in a gravity well, but the relative speed thing always stumped me.


if one twin were wearing frictionless ideal rollerskates standing on a conveyor belt moving at half the speed of light while wearing an ideal spacesuit which preserved his life, and the other twin were standing next to the conveyor belt, would one twin age faster than the other?
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Re: Ask me a question

Unread postby davep » Tue 02 Jan 2007, 21:53:33

$this->bbcode_second_pass_quote('davep', 'U')nless there was something to actually brake it, the wheels would skid and the plane would advance anyway.


Given they are frictionless, this would certainly happen.
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Re: Ask me a question

Unread postby Chicken_Little » Tue 02 Jan 2007, 21:55:46

$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('davep', 'U')nless there was something to actually brake it, the wheels would skid and the plane would advance anyway.


Given they are frictionless, this would certainly happen.


Assume the plane remains perfectly aligned relative to the conveyor belt.

Assume the plane's construction is perfect and the plane is perfectly balanced.
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Re: Ask me a question

Unread postby davep » Tue 02 Jan 2007, 21:58:57

$this->bbcode_second_pass_quote('Chicken_Little', '')$this->bbcode_second_pass_quote('davep', '')$this->bbcode_second_pass_quote('davep', 'U')nless there was something to actually brake it, the wheels would skid and the plane would advance anyway.


Given they are frictionless, this would certainly happen.


Assume the plane remains perfectly aligned relative to the conveyor belt.


How can you assume this? The mere contact between the tyres and the conveyor belt do not mean that they will remain aligned. Indeed, this is the crux of your (recently modified) question. I say that the thrust of the engines will mean that the plane will advance and that the conveyor belt will be unable to stop it.

So there.

Unless you're saying that the force of the friction on the tyres equals that of the engines (or something, any engineers that can bail me out here?)
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Re: Ask me a question

Unread postby cynicalheretic » Tue 02 Jan 2007, 22:00:52

This conversation is over, can I get a real question now... or can't you all come up with anything challanging?
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