A plane on a runway, how smart is r3vlimited?

[dirty30]

what if you take a sailboat, then put a huge fan on the boat and aim it at the sail... then turn it on.... will it move the boat?

[george graves]

HAHAHAHAHAHH!

[Justin B]

lmao. You guys have no idea what you're talking about. Sorry. but I've explained this in detail probably 5 times already now. Nice animation though James, funny. Thats a way to look at it, but it is NOT what the question asks. I am not over thinking this, you guys just fail to look at the glaringly obvious detail. You're going to need that belt to go thousands of miles per hour, ASSUMING the wheels can hold up to it (they wont), to make the drag on the wheel bearings high enough that the jet cannot possibly overcome the drag of some bearings. WTF? Of course thats ridiculous. Its probably next to impossible anyway. Do yourselves a favor and look t the original post if you're going to spend time drawing, or even trying to find an animated GIF like that and look at those words "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)." Hmm. Is that plane moving in that picture or in either one of your thoughts?? Not quite. Obviously you overlooked the whole point of the question. Its a trick, people will think like you guys and get all flustered and think people ho figured it out are morons, when infact you just need to open up your eyes :) The plane is moving forward as fast as the conveyor is going backwards, for the 100 billionth time, the wheels free spin, its not a damn car. Even if it was, worded in the same way, the car will still go forward since the question requires movement. The wheels will just spin twice as fast as the plane is vs the ground outside the belt. Its the belt moving backwards + the same speed of the plane moving forwards by the thrust of the JETS NOT THE WHEELS. Oy. Planes dont go forward by driving their wheels on the ground then once theyre in the air kick on their engines... lOL

Edit - Even if they did, which they dont, obviously, it would still work. Plane moves forward in relation to ground, belt moves backwards at that same speed, wheels think the plane is going twice as fast as it really is.

[Justin B]

We already seem to have gone over that a million times...

[Axxe]

That GIF is wrong. The conveyer doesn't apply any force on the plane directly, just through the wheels, which can be assumed as frictionless.

[James Crivellone]

[BENdashdash]

doesnt matter what the plane is being propelled by. heck, you can even push it. the belt will match that speed, thus causing the plane to go nowhere. simple as that.

/thread

[Justin B]

The wheels are free wheeling. Thats not where the plane gets the thrust and forward movement from. Its from the jets, once again, if the conveyor belt is moving backwards, and the plane has thrust going forwards, the wheels will be spinning out from underneath the plane, then the thrust from the jets will overcome the little bit of extra resistance (which isnt even in the theoretical problem at the beginning of the thread) from the rearward movement of the belt, but most importantly, push the plane forward as well. The belt will only go backwards as fast as the plane advances FORWARDs in relation to the ground beside the belt. The length of this belt would have to be at least as long or longer than a normal runway.

Am I going to be a lifer just from post counts explaining this to people? :crazy:

[BENdashdash]

answer me this. how can the plane move if the belt is moving as fast as the plane is?

[Justin B]

E30 Wagon, gotcha :). I understand, and yes that would be funny.

Ben, the wheels on the bottom of the plane are relatively free rolling. The plane will go forwards relative to the ground beside the conveyor belt, while the conveyor belt goes backwards, the wheels just spin twice as fast as they need to. Maybe a little extra thrust to get over the slight drag created by the faster wheels. I understand your position if you didnt read anything, I thought the same way till it finally clicked.

Edit -

Alrighty, aside from the fact that there are now motherfuckin' snakes on the plane and we all know that opens up a whole new set of problems, let's get back to the original text. It states that the belt matches the speed of the plane, NOT the thrust of the plane. You are underthinking this whole thing.

lol. thank you.

[RCWells]

no, dont have to. if the plane is thrusted by jet(s) and the conveyer belt will match the thrust, there is no way it would move, let alone lift. you guys are just overthinking this way too much. same if one were to try and push the plane while standing on the belt, it wouldnt move.

Alrighty, aside from the fact that there are now motherfuckin' snakes on the plane and we all know that opens up a whole new set of problems, let's get back to the original text. It states that the belt matches the speed of the plane, NOT the thrust of the plane. You are underthinking this whole thing.

[BENdashdash]

Ben, did you read anything?

no, dont have to. if the plane is thrusted by jet(s) and the conveyer belt will match the thrust, there is no way it would move, let alone lift. you guys are just overthinking this way too much. same if one were to try and push the plane while standing on the belt, it wouldnt move.

You're still thinking it acts like a car. If it is in neutral, the jet will push the car forward. Even if it was slowly, the conveyor would have to be moving at ridiculous speeds to cancel out the propulsion of the jet itself through the drag of the drivetrain in neutral. Unless thats what you mean, which would have to be the case to keep the car still.

That is what i mean and I realize the conveyor belt would have to moving at rediculous speeds. That's why it was fun to picture Jordan's e30 on it. The problem says that the conveyor belt will match the speed of the plane, which is generated by the propulsion of the jet.

[Brew]

I can't believe people are still arguing this.

Forget the plane, picture a missile sitting on the same runway with a few casters on it. Someone try and tell me that it wont accelerate, I dare you.

[adept]

What the hell do the wheels matter to the plane taking off? Of course it will take off.