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BanZu
United States3329 Posts
An airplane is on a treadmill and they move in opposite directions. When the airplane's engines are running at full power the airplane's speed is the same as the treadmill's speed. Will the airplane be able to take off? Or will it simply stay in place? #2 A helicopter is on a turn-table. When the helicopter's blades are at full speed the turn-table rotates in the opposite direction at the same speed. Will the helicopter be able to take off? Or will it simply stay in place?    | ||
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inReacH
Sweden1612 Posts
No and+ Show Spoiler + no. | ||
TheMango
United States1967 Posts
not sure on #2... but I'm thinking it will take off, because there will still be an updraft force lifting the helicopter, but I can easily see it spinning out of control on takeoff... | ||
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SnowFantasy
4173 Posts
#2 i don't know but its probably he same answer | ||
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LuckyFool
United States9015 Posts
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BanZu
United States3329 Posts
On February 21 2009 12:49 SnowFantasy wrote: #1 was tested on myth busters. #2 i don't know but its probably he same answer My friend said that the experiment for #1 was really bad | ||
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BanZu
United States3329 Posts
On February 21 2009 12:49 LuckyFool wrote: To generate lift doesn't the plane have to actually be moving through air? If it's stationary it doesn't really matter how fast it's moving there'll never be any lift generated. That's what I thought. Since the plane isn't moving relative to the Earth, there's no wind passing under the plane. My friends and I were discussing this for a while and we couldn't reach a solid conclusion. | ||
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LxRogue
United States1415 Posts
Fancy pic to prove my point. ![[image loading]](http://www.daviddarling.info/images/airfoil_streamlines.jpg) | ||
micronesia
United States24805 Posts
On February 21 2009 12:12 BanZu wrote: This doesn't make sense to me. The plane's motion is dictated by the engines... the wheels have nothing to do with it... if the engines are running full blast... the plane will move at the same speed relative to the air, regardless of if the ground is moving backwards or not.#1 An airplane is on a treadmill and they move in opposite directions. When the airplane's engines are running at full power the airplane's speed is the same as the treadmill's speed. Will the airplane be able to take off? Or will it simply stay in place? #2 A helicopter is on a turn-table. When the helicopter's blades are at full speed the turn-table rotates in the opposite direction at the same speed. Will the helicopter be able to take off? Or will it simply stay in place? This doesn't seem clearly defined. First of all, is the helicopter in the center of the turntable? I'll assume so. I assume you mean the angular velocity of the rotors is the same as the turntable (except opposite). In this case, the rotors are not moving relative to the air and nothing happens. | ||
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micronesia
United States24805 Posts
#1b: A plane is trying to take off. The speed that the plane normally travels to take off is 500 miles per hour. There is a steady 500 mph headwind. Will the plane be able to take off even though it is initially stationary in the horizontal direction? | ||
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BanZu
United States3329 Posts
On February 21 2009 12:55 micronesia wrote: This doesn't make sense to me. The plane's motion is dictated by the engines... the wheels have nothing to do with it... if the engines are running full blast... the plane will move at the same speed relative to the air, regardless of if the ground is moving backwards or not. I thought that if an engine was running at full power it still isn't enough to lift the airplane. Therefore the plane could only move forward on it's wheels like a car. And since it's running at the same speed as the treadmill it stays in the same place relative to the treadmill/Earth, which means there's no airflow under the wings to lift it up. ??? | ||
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Archaic
United States4024 Posts
On February 21 2009 12:58 micronesia wrote: Let me propose an alternate #1 perhaps... #1b: A plane is trying to take off. The speed that the plane normally travels to take off is 500 miles per hour. There is a steady 500 mph headwind. Will the plane be able to take off even though it is initially stationary in the horizontal direction? I love you micronesia. Not only reiterating these completely unrealistic riddles into truth, and then bringing physics into it all. And no for both of them anyways. We need more of these. | ||
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BanZu
United States3329 Posts
On February 21 2009 13:04 Archaic wrote: I love you micronesia. Not only reiterating these completely unrealistic riddles into truth, and then bringing physics into it all. And no for both of them anyways. We need more of these. Can you explain why? I tried to explain why they couldn't buy my friends wouldn't buy into it. EDIT: I mean the first one | ||
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inReacH
Sweden1612 Posts
On February 21 2009 13:07 BanZu wrote: Can you explain why? I tried to explain why they couldn't buy my friends wouldn't buy into it. EDIT: I mean the first one Think about what actually gives life to the airplane, is it the speed of the wheels? Of course not, it is the wing interacting with the matter in the air, so if the interaction between those two things is the same as if the wheels weren't moving at all, you aren't getting off the ground. | ||
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micronesia
United States24805 Posts
On February 21 2009 13:02 BanZu wrote: I thought that if an engine was running at full power it still isn't enough to lift the airplane. Therefore the plane could only move forward on it's wheels like a car. And since it's running at the same speed as the treadmill it stays in the same place relative to the treadmill/Earth, which means there's no airflow under the wings to lift it up. ??? I don't totally understand your confusion, but let me point out that a car uses engine power to turn wheels... and that is what makes the car go forward. Unlike a car, a plane uses engines to pull air through them and propel the plane forwards. | ||
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BanZu
United States3329 Posts
On February 21 2009 13:13 micronesia wrote: I don't totally understand your confusion, but let me point out that a car uses engine power to turn wheels... and that is what makes the car go forward. Unlike a car, a plane uses engines to pull air through them and propel the plane forwards. Yea, but I thought that the wind pulled by the engine itself wasn't enough. Is it? | ||
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micronesia
United States24805 Posts
On February 21 2009 13:17 BanZu wrote: Yea, but I thought that the wind pulled by the engine itself wasn't enough. Is it? If you think the plane applies a torque the wheels, which helps to accelerate the plane, then you are not correct. | ||
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Archaic
United States4024 Posts
Given the high speeds, the treadmill would simply turn the wheels, but not actually move the plane back significantly, assuming the plane was moving forward from the engines. I retract my statement about it not working. The plane would take off. | ||
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ieatkids5
United States4628 Posts
On February 21 2009 12:58 micronesia wrote: Let me propose an alternate #1 perhaps... #1b: A plane is trying to take off. The speed that the plane normally travels to take off is 500 miles per hour. There is a steady 500 mph headwind. Will the plane be able to take off even though it is initially stationary in the horizontal direction? it seems like the plane should just move vertically, since the way the wings are designed causes higher pressure below the wing, forcing the plane up. but since the plane isnt continuing in a forward motion, the plane will only stay in the air as long as there is a 500 mph wind. and the plane wont move forward or backward either, only up or down (assuming the 500mph wind doesnt push the plane). | ||
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BanZu
United States3329 Posts
On February 21 2009 13:18 micronesia wrote: If you think the plane applies a torque the wheels, which helps to accelerate the plane, then you are not correct. No, I know that's not how a plane works. So what you're saying is that if a giant clamp was holding a plane in mid-air and only let go when the engines were at full power the plane would automatically be able to fly because there's enough air flow under the wings? | ||
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