Riddle of the day November 17, 2005, 01:37:23 PM A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).The question is:Will the plane take off or not?Note: SRV1 is disqualified! Quote Selected
Riddle of the day Reply #1 – November 17, 2005, 01:43:12 PM No.If they're moving at the same speed, but opposite directions, there is no more wind to create lift than if it were sitting still. (I assume since they are moving at the same speed that you mean the wheels of the plane are moving, not the plane) Quote Selected
Riddle of the day Reply #2 – November 17, 2005, 01:43:34 PM No......needs airflow over the wings......Regardless of the thrust, if the plane is not moving forward, it won't get any lift. Quote Selected
Riddle of the day Reply #3 – November 17, 2005, 01:52:51 PM Quote from: Chuck WRegardless of the thrust:tg: Quote Selected
Riddle of the day Reply #4 – November 17, 2005, 01:58:46 PM YES!Is it the Harrier Jump Jet? Quote Selected
Riddle of the day Reply #6 – November 17, 2005, 02:30:41 PM NO, Ill get technicalFor an airplane to fly, it must always engage in a tug of war between the opposing forces of lift versus weight and thrust versus drag. For a moment, think of an airplane moving from right to left and the flow of air moving from left to right. The weight or force due to gravity pulls down on the plane opposing the lift created by air flowing over the wing. Thrust is generated by the propeller and opposes drag caused by air resistance to the airplane. During take off, thrust must be greater than drag and lift must be greater than weight so that the airplane can become airborne. For landing thrust must be less than drag, and lift must be less than weight Quote Selected
Riddle of the day Reply #7 – November 17, 2005, 04:35:46 PM Well, two people have it right, but for the wrong reason/no justfication. Quote Selected
Riddle of the day Reply #8 – November 17, 2005, 04:42:32 PM Quote from: JeremyBWell, two people have it right, but for the wrong reason/no justfication.Well who has it right and what is the reason. Quote Selected
Riddle of the day Reply #9 – November 17, 2005, 04:51:31 PM Quote from: t-bird85Well who has it right and what is the reason.Yeah, WTF?! :D Quote Selected
Riddle of the day Reply #10 – November 17, 2005, 04:53:39 PM The answer is yes. The conveyer belt only matches the speed of the plane. It is not trying to increase the treadmill speed to keep the plane's velocity to 0. So, if the plane is moving at 5mph, the conveyer is moving at 5mph in the opposite direction. The only thing slowing the airplane is the friction in the wheels. This is easily overcome by the thrust from the engines. Quote Selected
Riddle of the day Reply #11 – November 17, 2005, 04:54:48 PM QuoteWell who has it right and what is the reason.Judging by the fact that before he posted that 2 people were right.. there was 5 answers.. 3 were no, 2 were yes Plus he said the wrong reason/no justification4th quarter got it right but wrong reasonstuntmannick got it right but didn't justifyI should be sherlock holmes ;) Quote Selected
Riddle of the day Reply #12 – November 17, 2005, 05:00:48 PM Quote from: JeremyBThe answer is yes. The conveyer belt only matches the speed of the plane. It is not trying to increase the treadmill speed to keep the plane's velocity to 0. So, if the plane is moving at 5mph, the conveyer is moving at 5mph in the opposite direction. The only thing slowing the airplane is the friction in the wheels. This is easily overcome by the thrust from the engines.well then the question was deceitful. because you said the sensor tracks the plane's speed wouldn't the thrusters have something to do with the 'speed' so then the calculations to the track would make match that even when the thrusters are on.I think it's a trick question.. nobody ever said that the plain actually tried taking off. The question states taht the plane is standing on the runway.. then it just simply states 2 facts.. that the track moves one way and the plan moves the other. IT never stated that they are actually in that process of moving just that they can.It's like a car that's not turned on, it moves forwards or in reverse. but it's not actually in the process of doing so at that particular moment, its just what the car can do. Quote Selected
Riddle of the day Reply #13 – November 17, 2005, 05:01:31 PM Quote from: JeremyBThe answer is yes. The conveyer belt only matches the speed of the plane. It is not trying to increase the treadmill speed to keep the plane's velocity to 0. So, if the plane is moving at 5mph, the conveyer is moving at 5mph in the opposite direction. The only thing slowing the airplane is the friction in the wheels. This is easily overcome by the thrust from the engines.Yeah, that's why I used this little disclaimer. "(I assume since they are moving at the same speed that you mean the wheels of the plane are moving, not the plane)"If the plane is physically 'moving', then the wheels will be moving at twice the speed of the treadmill. You need to be more clear, proffessor. Quote Selected
Riddle of the day Reply #14 – November 17, 2005, 05:01:34 PM Quote from: JeremyBThe answer is yes. The conveyer belt only matches the speed of the plane. It is not trying to increase the treadmill speed to keep the plane's velocity to 0. So, if the plane is moving at 5mph, the conveyer is moving at 5mph in the opposite direction. The only thing slowing the airplane is the friction in the wheels. This is easily overcome by the thrust from the engines.There is a simpler explanation: The plane is not driven by its wheels, so turning the treadmill in the opposite direction will not slow the plane. Since the plane would travel at the normal speed that it would be travelling for a given amount of thrust, the plane would take off normally. The landing gear would take a beatinig, though - those wheels would be spinning FAST!!! Quote Selected
Topic: Riddle of the day (Read 1650 times)
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