If this is your first visit, be sure to check out the FAQ by clicking the link above.
You may have to register before you can post: click the register link above to proceed.
To start viewing messages, select the forum that you want to visit from the selection below.
Open ForumsThe Open forum was created for people to discuss anything else Non-Moto related. Just about anything goes! Please remember this is a loosely moderated area. If you do not have thick skin. We suggest you stay out of here.
a helicopter has a big enough prop to lift it vertically and enough power. I think that if a plane was built to allow a big enough prop, there is no way that you could keep it from taking off.
I think I remember reading somewhere once that according to physics, generally speaking a helicopter shouldn't be able to fly.
__________________
In Life, Try To Be The Kind Of Person Your Dog Thinks You Are...
2002 Kawasaki Ninja 250--SV-650 rear shock, Sonic Springs .80kg/mm front springs, ZX-2R graphics, flush mount front signals, tail pod rear signals, Kerker 2-1 race pipe, Factory Pro Stage 3 jet kit, UNI pod filters, ZG Double Bubble, Custom Creations soft vinyl seat cover, Kawi Green rim stripes, carbon brake fluid cap, carbon control levers, No Rear Fender, Yamaha R1 Style Mirrors, V-LEDs.com H4 HID Kit, Nelson Rigg Silver Streak Mini Saddle Bags, Rapid Transit Recon Tank Bag, Various Manufacturers Decals
Posts: 4,511
Casino Cash: $41108
Sportbike: See sig.
not physics.... common sense..... the theory among fixed winged pilots is, a hellicopter doesn't fly, it's just so damn ugly when it starts shaking, the earth rejects it.
Okay, other than this being the dumbest argument EVER, the question never stated what was powering the airplane. I will show the question again:
"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?
The question states that an airplane is standing (I didnt know they could stand) on a runway. It then states that is moves in one direction. The problemhere is that we do not know if it is being driven by its own power (aka. prop or jet) or if a little car is pushing it along.
That is where the problem lies.
If the plane is being pushed or pulled by a car/truck/bus/moped/person or any other "thing" where forward motion is dependent on the friction resistance created between the ground and itself, then the plane will go nowhere and thus not take flight.
If the plane is being pushed or pulled under its own power (aka. prop. or jet), the force created is being resisted by the AIR! not the ground. The ground is completely independent from the force created by the prop. or jet engine.
If anything, this question would be better worded if the plane were inside a wind tunnel.
The wheels have nothing to do with making a plane move. Ever wonder why airplanes crash when they lose their engines? No more force pushing them forwards. If the plane relied on its wheels to drive it, it would get off the ground BECAUSE THEY DON'T BUILD ROADS IN THE SKY!
Seriously, how can anyone think that that the wheels actually push the plane?
__________________
Quote:
Originally Posted by shah269
I was born in Iran, I don't believe in forgiving nor forgetting. I believe in getting even. Pay back is gonna be a bitch...
Last edited by VTEC_EATER : 02-26-2007 at 07:02 PM.
Ok, the key here is that the conveyor is matching the PLANE's speed and not the WHEELS' speed. It must be assumed the wheels of the plane are relatively frictionless. If the plane is traveling at 100 mph to the left, the conveyor will travel 100 mph to the right. This means that the wheels are spinning at 200 mph. The wheels don't drive the plane and don't control it's movement in any way. They are simply frictionless bearings between two surfaces. So, since they're frictionless, one surface can be moving at any velocity and have no effect on the other surface. So the plane can still move at 100 mph to the left without being affected by the conveyor moving 100 mph in the opposite direction. So yes, the plane will take off.
If you say that the conveyor matches the speed of the wheels, there is a physical restraint on the system that says the plane has 0 relative velocity and cannot takeoff.
As one who minored in Aerospace Engineering.....
I say,"Congratulations!!! You sir, win the Bernoulli Award!!!"
__________________ Able to split an infinitive at the speed of sound!
the plan will take off because its wheels only move when the plane is in motion. planes are not wheel drivin..so inorder for the conveyour to match speed the plane has to be moving in the first place i think it is plausable as myth busters would say. however a car could be on the same conveyour and not move an inch because a cars wheels can move or spin without the car moving like in a burnout. planes wheels only turn when plane is in motion
Posts: 7,630
Casino Cash: $83675
Sportbike: None! Sold it!
It's the wording of this problem that makes people want to argue.....
I'll try to explain.... (yes, the plane will take off).
I'll use the rolly chair example, using a rope to pull yourself toward a wall. I like that.
You're sitting there. Not moving. The conveyor is not moving.
You pull on the rope to take yourself closer to the wall. Say you go at 5mph for a second. The conveyor will ALSO move at 5mph for one second.
The wheels will spin at 10mph. 5 mph forward from the chair, 5mph backward from the conveyor.
The speed of the conveyor MATCHES the speed of the chair. But guess what? You're still ONE pull closer to that fucking wall than when you started.
The wheels spinning at twice the speed you are actually moving will create a little more friction.... but you ARE going to move forward.
NOW- if this were a CAR, it would be like someone walking behind you pushing the chair. They take a step forward, the conveyor moves back a bit. You get nowhere.
I hope that clears it up just a tad.
The question makes it seem like the plane can't get any forward momentum. But it just says that it matches the wheel speed.
It's a dumb question.
__________________
Moderator of Rider's Gear and Help me Fix it.
PM me if you have questions, concerns, or beer you need to give away.
Ok, the key here is that the conveyor is matching the PLANE's speed and not the WHEELS' speed. It must be assumed the wheels of the plane are relatively frictionless. If the plane is traveling at 100 mph to the left, the conveyor will travel 100 mph to the right. This means that the wheels are spinning at 200 mph. The wheels don't drive the plane and don't control it's movement in any way. They are simply frictionless bearings between two surfaces. So, since they're frictionless, one surface can be moving at any velocity and have no effect on the other surface. So the plane can still move at 100 mph to the left without being affected by the conveyor moving 100 mph in the opposite direction. So yes, the plane will take off.
If you say that the conveyor matches the speed of the wheels, there is a physical restraint on the system that says the plane has 0 relative velocity and cannot takeoff.
What system and who says????
If the plane is moving forward, what would be the difference in the conveyor matching the planes speed vs. matching the wheels speed. Wouldn't the wheels and the plane be moving at the same speed? Unless the plane leaves the wheels behind.
If a man said something, and a women was around to hear him, would he still be wrong???????
Posts: 2,598
Casino Cash: $18852
Sportbike: 2006 Yamaha Roadliner S with Stratoliner stuff added.
Quote:
Originally Posted by OreoGaborio
not physics.... common sense..... the theory among fixed winged pilots is, a hellicopter doesn't fly, it's just so damn ugly when it starts shaking, the earth rejects it.
I thought helis fly by beating the air into submission.
This question is all fine and good but what about those questions that make you go hummmmmmm. Those questions that have been asked for thousands of years. Kind of like these below.
1) Why are there jumbo shrimp? How can you have an extremely large very small item.
2) Why do they call it military intelligence? It is obvious that thats an oxymoron.
3) If a tree falls in the woods when no one is around does it make any noise?
4) Does the little light really go out when you shut the door on the fridge?
5) We do things because "they" say we should or say things because "they" said we should well who the hell are they and why the hell do we listen to them?
It took me a little bit to look at it, but I think I'm starting to see what's going on. The people who say that it won't take off are the ones who believe that the plane won't move forward. I agree with this, if the plane didn't move forward, then it wouldn't take off.
However, we're facing confusion in what produces the forward motion. Let's say you have a car standing on that treadmill runway with all of the same speed-matching conditions. The car won't move anywhere since whatever speed the engine spins the wheels at, the runway moves backwards. That means if you've got a wheel circumference of one meter (just to make things simple, I know it's not right), then for every rotation of the wheel, the runway will move back by one meter. The car won't go anywhere because the forward motion is provided by the wheels rolling forward, almost, crudely put, pushing off of the ground.
The airplane turbine, in the same crude way, is pushing off of the air. That's where the rolling chair and rope analogy comes from, I think. The rope is the air, and the air doesn't move. So, when the plane turns up its turbines, they push off of the stationary air. Then, for every revolution of the plane's wheel (let's say the same meter) the treadmill moves back one meter. Except what happens is since there's no driving force being applied on the plane wheels - they're not connected to an engine - they simply spin twice as fast and the plane moves forward. As someone said above, they act like bearings. Thus, since the plane is pushing against the air and not against the ground (like a car would), the plane moves forward and does take off. The thrust of the turbines moves the plane forward, from where Bernoulli takes over. However, you still need a full-length runway for this plane.
BRAVO!!!!
__________________ Able to split an infinitive at the speed of sound!
WIRED-LEESTA
Linear Mode
