nmt_oli Posted February 22, 2006 Report Share Posted February 22, 2006 Jet engines suck air in, and push it out the back. this creates thrust which moves the plane forward, and the friction between the ground and the plane is small in comparison to the force of the trust applied. this conveyor situation effectively doubles the friction, but this is not enough to make a difference.So, the plane moves forward, air moves over the wings and creates lift, the plane takes off.The enignes themsleves will not draw enough air over the wings to make the plane take off- the engine hangs below the wings, and air travels through them.Who said the conveyor belt monitors the speed of the wheels? It says it just matches the potential speed the aircraft would be travlling if it were on stationary ground....C'mon this is basic mechanics!!!!no one said the conveyor measures the speed of the wheel, but it doesnt measure the speed of the engines either- it measures the speed of the plane, which coincedentally is directly proportional to the speed of the wheels (but not proportional to the speed of the engines, as they supply thrust, so its a very differnt propulsion method to a car) Link to comment Share on other sites More sharing options...
andyroo Posted February 22, 2006 Report Share Posted February 22, 2006 (edited) Conveyor belt matches speed of the aircraft... aircraft increases thrust, speed relative to stationary point increases, conveyor belt monitors speed, and increases to the same in the opposite direction, the aircraft will not move.Stop saying friction, I dont know why you keep saying it cos its got nothing to do with anything Edited February 22, 2006 by andyroo Link to comment Share on other sites More sharing options...
mod_rider Posted February 22, 2006 Report Share Posted February 22, 2006 This is all way more complicated than it needs to be. If there's a conveyer belt going the oppositte way which in effect is countering the planes acceleration, it will keep the plane stationary. A plane will not leave the ground unless there is wind flowing towards it. Putting it on a conveyer belt will have the same effect as taking the wings off almost.Anyway, it won't take off unless this is a trick question Link to comment Share on other sites More sharing options...
nmt_oli Posted February 22, 2006 Report Share Posted February 22, 2006 Friction has a lot to do with it. think about this problem simply, and read my posts again- ive already said this.THE PLANE DOES MOVE. if the plane is stationary, so is the conveyor- but for the conveyor to move, the plane MUST move, as the speed of the conveyor is controlled by the speed of the plane NOT the speed of the engines.The wheels of a plane hold it off the ground and spin freely, therefore a conveyor will not move a plane. In reality, a plane on aconveyor belt will move due to friction in the wheels- however, as soon as the force from the trust equals the frictional force inthe wheels, the plane will become stationary with the conveyor moving underneath it- but that doesnt relate to this problem as in this problem if the plane was stationary, the belt would stop. Link to comment Share on other sites More sharing options...
Brian Bleech Posted February 22, 2006 Report Share Posted February 22, 2006 if its a front propeller plane then yes - as the prop will force aire over the wing and eventually that will be enough to lift the plane up!! Link to comment Share on other sites More sharing options...
nmt_oli Posted February 22, 2006 Report Share Posted February 22, 2006 If a propellor plane was standing on the ground, braked and chocked so it couldnt go anywhere and it was spun up to full throttle, it would not lift, the props do not move enough air over the plane. to lift, a plane needs to have all the air around it moving relative to it, so the plane needs to be moving, or in a headwind. this is due to the length of the wings.In this riddle, the plane would take off if it is proppellor, jet, rocket powered! it makes nooo difference. Link to comment Share on other sites More sharing options...
Tony Harrison Posted February 22, 2006 Report Share Posted February 22, 2006 if its a front propeller plane then yes - as the prop will force aire over the wing and eventually that will be enough to lift the plane up!!You cleared failed GCSE Physics. That is not how aeroplanes work - if it was we would obviously have had vertical take-off propellor planes... Also, jet engines do not turn an aeroplanes wheels - there is no drive to the wheels, they are simply mounted on free-turning bearings.nmt_oli seems to be about the only person with a brain here. The jet engines use thrust to push against the air around the plane, and hence the fact that the wheels are being turned by a conveyor shouldn't make a whole lot of difference. Link to comment Share on other sites More sharing options...
nmt_oli Posted February 22, 2006 Report Share Posted February 22, 2006 At last! another person with common sense! Link to comment Share on other sites More sharing options...
Brian Bleech Posted February 22, 2006 Report Share Posted February 22, 2006 (edited) If a propellor plane was standing on the ground, braked and chocked so it couldnt go anywhere and it was spun up to full throttle, it would not lift, the props do not move enough air over the plane. to lift, a plane needs to have all the air around it moving relative to it, so the plane needs to be moving, or in a headwind. this is due to the length of the wings.In this riddle, the plane would take off if it is proppellor, jet, rocket powered! it makes nooo difference.depends of the plane, some weird freaky looking plane could do it like that Actually i understand it and it depends on how you interperate the riddle, if you assume the plane is keep stationary then there is NO chance the plane would take off, but for the convoyer belt to do this, The wheels would have to be attached to the engine, but they are not!You cleared failed GCSE Physics. That is not how aeroplanes work - if it was we would obviously have had vertical take-off propellor planes... Also, jet engines do not turn an aeroplanes wheels - there is no drive to the wheels, they are simply mounted on free-turning bearings.nmt_oli seems to be about the only person with a brain here. The jet engines use thrust to push against the air around the plane, and hence the fact that the wheels are being turned by a conveyor shouldn't make a whole lot of difference.that was 10 years ago - brain fade!! haha i was failing a - level does that count,so i gave up!!! Edited February 22, 2006 by leedstrials Link to comment Share on other sites More sharing options...
nmt_oli Posted February 22, 2006 Report Share Posted February 22, 2006 exactly, you can't just assume the plane stays stationary, you have to think about it. this is by no means a hard riddle, it TELLS YOU the plane moves, its just most people seem to assume it doesnt. i have had to work much harder to work out other riddles/trick questions whatever you wanna call them. Link to comment Share on other sites More sharing options...
andyroo Posted February 22, 2006 Report Share Posted February 22, 2006 You cleared failed GCSE Physics. That is not how aeroplanes work - if it was we would obviously have had vertical take-off propellor planes... Also, jet engines do not turn an aeroplanes wheels - there is no drive to the wheels, they are simply mounted on free-turning bearings.nmt_oli seems to be about the only person with a brain here. The jet engines use thrust to push against the air around the plane, and hence the fact that the wheels are being turned by a conveyor shouldn't make a whole lot of difference.You mean a helicopter Until the aircraft leaves the ground, the wheels are everything to do it. They may not drvie the plane, but without them the plane would go nowhere.Lets make things simpler and look at the conveyor belt if it only had one speed.The plane has no thrust, it will move backwards along in the direction of the conveyor belt.It increase thrust, and matches the speed of the conveyor belt. (i.e, if the conveyor belt and stationary runway were side by side, and the aircraft moved in the same direction as the conveyor belt on the stationary runway at the same speed so the anything on the belt would stay next to the plane) to a bystander on stationary ground, the aircraft will appear stationary.If the aircraft increase thrust some more and the conveyor stays the same, it will move forward.HOWEVER, this conveyor belt increase speed in the oppposite direction as the plane increse thrust, so the aircraft will remain stationary. Link to comment Share on other sites More sharing options...
mink Posted February 22, 2006 Report Share Posted February 22, 2006 Another riddle: Three identical cylinders are filled with unknown quantities of ideal gases. The cylinders are closed with identical frictionless pistons of mass M. Cylinders A and B are in thermal equilibrium with the room at 20 oC, and cylinder C is kept at a temperature of 80 oC. Is the pressure of Nitrogen gas in cylinder A greater than, less than, or equal to the pressure of the Hydrogen gas in cylinder B? Is the pressure of Hydrogen gas in cylinder C greater than, less than, or equal to the pressure of Hydrogen gas in cylinder B? Why? Link to comment Share on other sites More sharing options...
andyroo Posted February 22, 2006 Report Share Posted February 22, 2006 exactly, you can't just assume the plane stays stationary, you have to think about it. this is by no means a hard riddle, it TELLS YOU the plane moves, its just most people seem to assume it doesnt. i have had to work much harder to work out other riddles/trick questions whatever you wanna call them.The riddle tells you the plane moves in one direction and the conveyor belt moves in the other. To someone standing on the conveyor belt, the plane will move away from them, but to someone standing on stationary ground, the plane will be stationary. Link to comment Share on other sites More sharing options...
Tony Harrison Posted February 22, 2006 Report Share Posted February 22, 2006 When I said plane I meant aeroplane (wings) rather than helicopter.For those who are simply too stupid to deviate from what appears obvious, click here. Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted February 22, 2006 Report Share Posted February 22, 2006 Your telling me if you walked up a down escalator at the same speed it moves down at, you will reach the top? Or will you have to increase your speed? (and in this example, the escalator would match your speed in the opposite direction, and you would still go nowhere)NO! The aircraft is applying force to the air, the wheels just happen to turn because on the floor. It is not being driving through the wheels.The plane would not stay still it would accelerate off. Link to comment Share on other sites More sharing options...
Tony Harrison Posted February 22, 2006 Report Share Posted February 22, 2006 Three identical cylinders are filled with unknown quantities of ideal gases. The cylinders are closed with identical frictionless pistons of mass M. Cylinders A and B are in thermal equilibrium with the room at 20 oC, and cylinder C is kept at a temperature of 80 oC. Is the pressure of Nitrogen gas in cylinder A greater than, less than, or equal to the pressure of the Hydrogen gas in cylinder B? Is the pressure of Hydrogen gas in cylinder C greater than, less than, or equal to the pressure of Hydrogen gas in cylinder B? Why?Are they not all at atmospheric pressure (1 bar) if the pistons are stationary? Link to comment Share on other sites More sharing options...
Brian Bleech Posted February 22, 2006 Report Share Posted February 22, 2006 (edited) You mean a helicopter Until the aircraft leaves the ground, the wheels are everything to do it. They may not drvie the plane, but without them the plane would go nowhere.Lets make things simpler and look at the conveyor belt if it only had one speed.The plane has no thrust, it will move backwards along in the direction of the conveyor belt.It increase thrust, and matches the speed of the conveyor belt. (i.e, if the conveyor belt and stationary runway were side by side, and the aircraft moved in the same direction as the conveyor belt on the stationary runway at the same speed so the anything on the belt would stay next to the plane) to a bystander on stationary ground, the aircraft will appear stationary.If the aircraft increase thrust some more and the conveyor stays the same, it will move forward.HOWEVER, this conveyor belt increase speed in the oppposite direction as the plane increse thrust, so the aircraft will remain stationary. nope it won't! (well it will but only very slightly due to friction of hubs and stuff) , because the wheels are independant of the engine!! they are free moving. Go home a put a firework on a toy car and use something as a conveyor belt!! Edited February 22, 2006 by leedstrials Link to comment Share on other sites More sharing options...
Tony Harrison Posted February 22, 2006 Report Share Posted February 22, 2006 No leedstrials, he is saying with 'no thrust' the plane will move backwards, as there is friction in the wheels. As soon as there is any thrust, the movement of the conveyor belt is neglible and we can forget it. Link to comment Share on other sites More sharing options...
andyroo Posted February 22, 2006 Report Share Posted February 22, 2006 When I said plane I meant aeroplane (wings) rather than helicopter.For those who are simply too stupid to deviate from what appears obvious, click here.A wing works on the same principle as a propeller. A wing remains staionary and air is pushed over it, whereas a propeller moves through stationary air. Bothe provide lift through the shape of the wing/prop.Right derf...You are sitting in a trolly on a running machine. you are holding onto the bars either side of the running machine, so the trolley is stationary and the wheels are spinning at a gentle pace. You push against the bars to move yourself in the trolley along the running machine in the opposite direction that it is moving. The amount of force required to do it is more than you need to remain stationary.BUT as you increase the force needed to do it, the running machine increses speed. Now it requires more force to hold yourself stationary, and the more force you put into trying to move yourself forward, the faster the running machine goes. You put more and more force into keeping yourself stationary, until it becomes too much, you let go and end up in a heap across the gym.Get it yet? Link to comment Share on other sites More sharing options...
Tony Harrison Posted February 22, 2006 Report Share Posted February 22, 2006 A wing works on the same principle as a propeller. A wing remains staionary and air is pushed over it, whereas a propeller moves through stationary air. Bothe provide lift through the shape of the wing/prop.No, the wing and propellor work on different principles (look at the blade cross-sections). My complaint, however, was that leadstrials was implying that the draft from the propellor would create enough air flow to lift the wings (Bernoulli effect).I do think though, that you should go and sign-up to a pyramid selling scheme. You'd make a fortune.And in case you didn't see it before, here's that link. Link to comment Share on other sites More sharing options...
nmt_oli Posted February 22, 2006 Report Share Posted February 22, 2006 But andyroo- the force required to hold your self stationary, or pull yourself forward is actually quite small, so it wouldnt be a problem. Link to comment Share on other sites More sharing options...
Tony Harrison Posted February 22, 2006 Report Share Posted February 22, 2006 Precisely. If the plane stayed still in relation to the ground, it would mean that all the power from the jet engine was being used to overcome the friction/inertia of the wheels (freely) turning on the conveyor belt. That's simply ridiculous.Some people just won't open their minds and think. They're convinced they've got the right answer and won't be told otherwise. Like the good old Monty Hall problem (goats and car) - but lets not get into that, it was in another thread. Link to comment Share on other sites More sharing options...
andyroo Posted February 22, 2006 Report Share Posted February 22, 2006 But andyroo- the force required to hold your self stationary, or pull yourself forward is actually quite small, so it wouldnt be a problem.But what im saying is that the harder you try to pull yourself forward, the harder the running machine will try and pull you back.And snappel... since when have you had anything to with aircraft? A wing and prop DO use the same principle to create lift, forming low pressure on the bottom and high on the top. Believe me - I did my A2 physics coursework on lift. And if a prop didnt create lift like a wing then why would you adjust the pitch of the prop to create different amounts of forward lift? Link to comment Share on other sites More sharing options...
Brian Bleech Posted February 22, 2006 Report Share Posted February 22, 2006 (edited) No leedstrials, he is saying with 'no thrust' the plane will move backwards, as there is friction in the wheels. As soon as there is any thrust, the movement of the conveyor belt is neglible and we can forget it. i assuming that he meant the plane would move back at the same speed as the conveyor belt, it wouldn't! (unless the brake was on) in 'perfect' conditions (infinate friction between the wheels/conveyor and no friction between wheel/axle) - if the convoyor belt was moving back a 50mph the wheels would turn at 50 mph - but the plane to the visable eye would appear stationary. Edited February 22, 2006 by leedstrials Link to comment Share on other sites More sharing options...
flipkickbs Posted February 22, 2006 Report Share Posted February 22, 2006 Whoever said it will take of is correct.Ian Link to comment Share on other sites More sharing options...
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