Aces High Bulletin Board
General Forums => The O' Club => Topic started by: muckmaw on November 17, 2003, 12:58:57 PM
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Need some help here.
If a plane flies from Los Angeles to NYC, it obviously must fly West to East.
If the planes top speed is 500MPH, but the earth below it is spinning at 1000 mph, how the hell does the plane ever get to NYC?
WOuld'nt it's ground speed by -500 mph?
Does the atmosphere rotate at the same rate as the earth?
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Yes.
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If the atmosphere didn't we'd have some wicked winds, trees would be bent on their sides and we'd be cave dwellers.
Well sorta
The atmosphere is in the "Gas" State... Gas still has density and mass, so anything that has mass can be acted upon by forces. So we move through air as fish move through water..
..... i think..
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So then flying in the atmosphere could be equated to swimming in the ocean, really.
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Originally posted by BlckMgk
If the atmosphere didn't we'd have some wicked winds, trees would be bent on their sides and we'd be cave dwellers.
Well sorta
The atmosphere is in the "Gas" State... Gas still has density and mass, so anything that has mass can be acted upon by forces. So we move through air as fish move through water..
..... i think..
Isnt it funny how if you stop and think about something we all take for granted, we realize how complicated it really is?
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Originally posted by muckmaw
Isnt it funny how if you stop and think about something we all take for granted, we realize how complicated it really is?
Kinda like when you guys think of me, huh?
:)
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Originally posted by muckmaw
Need some help here.
If a plane flies from Los Angeles to NYC, it obviously must fly West to East.
If the planes top speed is 500MPH, but the earth below it is spinning at 1000 mph, how the hell does the plane ever get to NYC?
WOuld'nt it's ground speed by -500 mph?
Does the atmosphere rotate at the same rate as the earth?
It's relativity thing man...
A train passes a station traveling east.
An observer at the station observse the train traveling N mph relative to his position.
A conductor on the train walks eastwarding at M mph...
An observer measures the conductors speed as N+M mph...
Add another train traveling west, a mirror, a flash light, a few party hats, naked women, psychotic drugs and you have the theory of relativity...
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The Earth is spinning/moving from west to east (left to right on a map) at 1,000 mph at the equator, 500 mph at 45 degrees north or south latitude, and 0 mph at the poles.
The plane still has this rotational speed, even after it takes off.
In the same way, a space ship still has the rotational speed of the earth as it takes off. That's why it saves fuel to launch rockets into earth orbit from near the equator: they get the maximum (1,000 mph) head start on achieving orbital velocity, about 17,500 mph, I think.
The atmosphere rotates with the earth, more or less. But any air mass moving towards the equator has LESS eastward velocity, and therefore moves west in relation to the surface. Air masses moving away from the equator have MORE eastward velocity than the atmosphere further from the equator, so it moves east. This is called the Coriolis effect. It explains why hurricanes, for example, have the rotation they do.
MRPLUTO
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Well, if you want to figure that plane's absolute speed you need to consider other things as well.
Our earth's speed around the sun: 170,000 kph
Our sun's speed through our galaxy: 70,000 kph
Our galaxy's rotational speed: 790,000 kph
Our galaxy's speed through our universe: who knows?
Jane, stop this crazy thing!
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Here is one which puzzled me:
Why is easier to keep your balance on a bycicle when you're moving than when you are staying still?
Ravs
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Originally posted by ravells
Here is one which puzzled me:
Why is easier to keep your balance on a bycicle when you're moving than when you are staying still?
Ravs
Gyro.
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Can you give more detail please Sandman? I am not a scientist.
Thanks
Ravs
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Originally posted by ravells
Can you give more detail please Sandman? I am not a scientist.
Thanks
Ravs
I'm not either... I was wrong. :)
What keeps a bike upright?
This is a classic trick question, as many people with some high school or college physics assume that it is the gyroscopic effect of the wheels that keeps a bike upright. But this is not the reason, and experiments with bikes that have counter-rotating wheels have demonstrated so. The reason a bike stays upright is largely two-fold: rider balance and "steering trail." Rider balance is simple enough to understand, but steering trail requires some explanation. Steering trail refers to the effect produced by the design and geometry of the front part of a bike whereby it tends to slightly correct itself when the front wheel is turned askew from the direction the bike is going. You can see this effect by holding a bike from its seat, pointing the bike north but pointing the front wheel slightly to the left or right and then pushing the bike forward. Notice how the front wheel adjusts itself towards the direction of bike motion. As for the gyroscopic effect of the wheels, only at very high speeds with heavy wheels do they begin to have any significant effect. A simple way to see how little effect gyroscopics have on bike balance is to prop your bike on a curb with the rear wheel off the ground while spinning as fast as you can get it. Then push the bike over. Notice that it falls over just as easily as when the wheel is still.
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Very interesting.
Thanks!
:)
Ravs
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Originally posted by ravells
Can you give more detail please Sandman? I am not a scientist.
Thanks
Ravs
gyro scopic force... instantious rotation around an axis....
the same force that keeps a top from falling over when it spins.
The force applied to make the wheel spin must be over come to rotate the axis.... so the faster the whell turns... the more force required to change the tilt of the axis.
F=MA.... force = mass times acceleration...
the mass of the rim of the wheel is going around the axis... the faster it goes... the greater the force it has... in order to tilt the axis... the rim also has to move... because it's held into place around the axis by the spokes... well since the rim as has an inertia F=MA going in one direction and constantly changing it's acceleration (instantious rotation around an axis)...a greater force must be applied to the axis inorder to change it's tilt... this same force is applied to the inertia of the rim... blah blah blah blah blah...
confused?... so am I.... don't ask me to explain physics... just look up the odd answer in the back of the book... disregard friction... and the numbers don't have to be precise.... fudge it.
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Just goes to confirm my belief that the world is indeed....flat.
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Thought a gyro was a pocket like sandwich.:p
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Just think of us as crabs on the bottom of the sea... wanting to be fish
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Originally posted by MRPLUTO
This is called the Coriolis effect. It explains why hurricanes, for example, have the rotation they do.
MRPLUTO
... and why toilets in Australia flush counter-clockwise :)
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There is no plane. ;)
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lolololol! AK Iron!
Inspired.
Ravs
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The atmosphere the plane is flying in is moving at the same speed as the earth's rotation.
It's the same reason you don't fly 300 feet down the the block everytime you jump in the air.
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The atmosphere rotating at the same speed of the earth has very little to do with it.
Example: If there were no atmosphere and you jumped you would still fall in the same spot.
Its all about relativity. The plane, even at standstill is travelling at the earths rotational speed (1000mph). When the plane takes off there are two primary forces acting on the plane (in relation to this question), inertia, and gravity. Inertia keeps the plane at speed relative to the earths spinning speed. In regards to the question the atmosphere only really provides relative drag (outside of the whole aerodynamics side), ie if the atmosphere were not rotating relative to the earths spin speed upon liftoff the plane would either have a 1000mph tailwind or headwind.
So the answer is inertia, gravity, and very little to do with atmosphere.
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Example: If there were no atmosphere and you jumped you would still fall in the same spot.
I 'Stand corrected' (get it? STAND CORRECTED??) I'm so funny...
:rofl
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Its ok Otto, I just had two cans of Red Bull and a bottle of V (a little wired right now).
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actually you land in the same spot you jumped from because you still have the speed that the earth is rotating with you...wich is the same reasoln why if you jump on a bus going down the highway you dont end up going through the bathroom wall...
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Originally posted by vorticon
actually you land in the same spot you jumped from because you still have the speed that the earth is rotating with you...wich is the same reasoln why if you jump on a bus going down the highway you dont end up going through the bathroom wall...
What happens if your bus is doing the speed of light and you jump up? ;)
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Originally posted by vorticon
actually you land in the same spot you jumped from because you still have the speed that the earth is rotating with you...wich is the same reasoln why if you jump on a bus going down the highway you dont end up going through the bathroom wall...
Umm... thats what I said.
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It's also means that if you as a passenger in that plane jumped in the air you wouldn't get slammed into the rear bulkhead at 1500 mph. Messy that!
But if you jump OFF the bus at 60mph you would continue to travel forward alongside the bus at 60 mph because relative to the bus you are not moving. Of course on Earth this lasts .3 of a second then gravity and drag ruins your whole day. In space this wouldn't happen. But the number 19A bus doesn't travel to the moon and back (it just feels like it!)
Fascinating things gyros. A spinning gyro will attempt to maintain it's position in SPACE not the Earth. So the gyros in the aircraft will attempt to tilt or topple back towards it's original position in space at a known rate. Precession. This of course makes them useful for navigation. I always found that fact to be quite weird. I mean how do gyros know??????
Plus if you apply a force to a spinning gyro it will react at 90 degrees to the applied force, again useful for attitude indicators in aircraft. You can prove this by spinning a wheel in your hands. If you try turn the wheel left or right it will resist with a force 90 degrees to the force applied by you.
Motorcyclists use this fact whether they know it or not. When travelling in a straight line at speed if the rider pulls on the left handlebar or pushes on the right handlebar the bike will tilt to the right and of course turns right. It's amazing how many experienced motorcyclists don't know this, countersteering it's called. But it's a function of gyroscopes which the front wheel is one.
Another interesting idea. If the earth is rotating at 500 mph at the latitude you are flying at and the aircraft is flying west at 500 mph. The sun never sets. Perpetual daylight.
Of course the Earth itself is a gyroscope and it tilts or precesses over time.
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Originally posted by cpxxx
Another interesting idea. If the earth is rotating at 500 mph at the latitude you are flying at and the aircraft is flying west at 500 mph. The sun never sets. Perpetual daylight.
If you manage to stay up for an entire year, it will eventually set at some mid point and then be in darkness for half a year. Then sunrise, sunset, and twilight would be around for a lot longer too.
-SW
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vulcan i just made it easier to understand for laymen (technically i am one...just over halfway through grade 11 physics...only just finishing up circular motion...)
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Originally posted by AKIron
What happens if your bus is doing the speed of light and you jump up? ;)
Oh yeah smart guy... what happens if you're in your car traveling at the speed of light, and turned on your headlights.. would they do anything?
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Originally posted by BlckMgk
Oh yeah smart guy... what happens if you're in your car traveling at the speed of light, and turned on your headlights.. would they do anything?
no as theoretically nothing can go faster than c, theoretically.
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Originally posted by cpxxx
Fascinating things gyros. A spinning gyro will attempt to maintain it's position in SPACE not the Earth. So the gyros in the aircraft will attempt to tilt or topple back towards it's original position in space at a known rate. Precession. This of course makes them useful for navigation. I always found that fact to be quite weird. I mean how do gyros know??????
Plus if you apply a force to a spinning gyro it will react at 90 degrees to the applied force, again useful for attitude indicators in aircraft. You can prove this by spinning a wheel in your hands. If you try turn the wheel left or right it will resist with a force 90 degrees to the force applied by you.
Its all to do with the fact that the wheel is actually accelerating as it spins (not a net acceleration in rotationial speed, but as each part of the wheel rotates it is constantly changing direction in movement which = acceleration and deceleration) and then I get all confused cos I'm rusty and the red bull has worn off.
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hahahhahaha:aok :rofl
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Originally posted by AKIron
What happens if your bus is doing the speed of light and you jump up? ;)
Time stops at the speed of light so I'm afriad you can't do anything, including stopping the bus and getting off.
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muckmaw: So then flying in the atmosphere could be equated to swimming in the ocean, really.
When flying east a plane weights about 1/400th less than when it is flying west.
Vulcan: If there were no atmosphere and you jumped you would still fall in the same spot.
That depends how high you were when you jumped. Your linear velocity up high would be greater than "the same"spot" on the Earth's surface, even if your angular velocity was the same.
AKIron: What happens if your bus is doing the speed of light and you jump up?
You will gain a lot of weight. You must also watch carefully juming in as the bus will seem to be infinitesmally short.
miko
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Originally posted by miko2d
Vulcan: If there were no atmosphere and you jumped you would still fall in the same spot.
That depends how high you were when you jumped. Your linear velocity up high would be greater than "the same"spot" on the Earth's surface, even if your angular velocity was the same.
Only if you believe in a flat earth.
Climb the highest mountain, jump, you'll land in the same spot. Find the lowest valley same thing.
Now, find the tallest cliff, jump off it, you do not suddenly speed away from the cliff even though in theory "1000mph" rotational speed at the top is higher than the speed at the bottom.
Why? Because of gravity. Gravity is constantly accelerating and decelerating us relative to the earths spin, just as in the gyroscopic effective discussed above.
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Vulcan: Now, find the tallest cliff, jump off it, you do not suddenly speed away from the cliff even though in theory "1000mph" rotational speed at the top is higher than the speed at the bottom.
Not speed away, no - you would move slightly to the east. The top of the cliff has greater linear velocity than the bottom.
If you stand on top of a 1000 ft cliff, you are doing extra ~6280 feet with every revolution of the Earth compared to the sea level.
A top of a cliff as high as the Earth's radius would be moving twice as fast as it's bottom.
The gravity would pull you straight down but your 1000mph horisontal velocity relative to the bottom would not go anywhere.
miko
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Originally posted by GScholz
Which is a myth, not reality.
Are you serious?
Quick, Vulcan, go flush your toilet and tell us which way it spins!
ed: you are from NZ, IIRC, right? :)
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Cor! so many Einstiens...so little time!
I have no idea about this stuff.
Ravs