Something amazing to tell you concerning physics and motion

[Sully]

Originally Posted by orange

No. Ideally the wheel only has move forward one point (0 distance) to start rolling.

So at some point the wheels are moving faster than the treadmill? And the treadmill must catch up?

[MagicHef]

Originally Posted by Sully

I'm just saying, niether the wheel nor the treadmill would ever move in this scenario...right?

Theoretically, no, unless someone came up and pushed on the treadmill or something.

[Buck]

So since the wheels on the plane are going the same speed traveling forward as the rest of the plane, the question is:

Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the plane, moving in the opposite direction. Can the plane take off?

I changed the word Wheels to Plane.

Thats the real question I guess.

[MagicHef]

Originally Posted by MediaCenterJunkie

So since the wheels on the plane are going the same speed traveling forward as the rest of the plane, the question is:

Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the plane, moving in the opposite direction. Can the plane take off?

I changed the word Wheels to Plane.

Thats the real question I guess.

No, the wheels can be moving at 5 ft/sec with the treadmill moving at 5 ft/sec in the opposite direction, and the plane will be moving at 0 ft/sec.

[Buck]

Originally Posted by MagicHef

No, the wheels can be moving at 5 ft/sec with the treadmill moving at 5 ft/sec in the opposite direction, and the plane will be moving at 0 ft/sec.

The wheels dont affect the plane moving, so the real question is if the treadmill is going the same speed as the plane, not the wheels.

[orange]

Originally Posted by MediaCenterJunkie

The wheels dont affect the plane moving, so the real question is if the treadmill is going the same speed as the plane, not the wheels.

Extrapolate from my answer in #185. As the wheel rotates, the plane's hypothetical forward speed equals circumference/(time/rotation); the conveyor belt's speed must equal this.

[MagicHef]

Originally Posted by MediaCenterJunkie

The wheels dont affect the plane moving, so the real question is if the treadmill is going the same speed as the plane, not the wheels.

The wheels are solidly attached to the plane, so they affect the motion of the plane in the sense that the speed of the plane in relation to the speed of the treadmill will always be equal to the speed of the wheels.

[Buck]

Originally Posted by MagicHef

The wheels are solidly attached to the plane, so they affect the motion of the plane in the sense that the speed of the plane in relation to the speed of the treadmill will always be equal to the speed of the wheels.

If the plane isn't moving forward relative to the ground, then its speed is 0, meaning the treadmill's speed is also 0, but that cannot be the case. The speed of the wheels in the original question was referring to the speed in which they were spinning.

Am I wrong here?

[orange]

Originally Posted by MediaCenterJunkie

So since the wheels on the plane are going the same speed traveling forward as the rest of the plane, the question is:

Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the plane, moving in the opposite direction. Can the plane take off?

I changed the word Wheels to Plane.

Thats the real question I guess.

The net speed (plane plus conveyor belt) must equal 0.

The plane will never move forward, there will be no lift generated and it won't take off.

[cdcox]

Actual wheels could not be spun fast enough to generate enough friction to overcome the thrust of jet engines.

[MagicHef]

Originally Posted by cdcox

Actual wheels could not be spun fast enough to generate enough friction to overcome the thrust of jet engines.

That is true.

[Simply Red]

MagicHef sure knows his 'Physics'

Sick 'EM, BOY!!!

[nstygma]

LOL
i just read a comment here about the plane crash in the ocean near Brazil. Which one of you posted it? reerun?

I love all the so-called "experts" on this thread stating what they call "facts" when they weren't even there. I've been a pilot for 47 years and I've been in this same situation at least 100 times. The first thing you learn in flight school (and trust me, this has saved me every time) is that right before you hit the ground, you jump up fast enough to counteract the descending speed. IMHO, these people just weren't paying attention.

[bdeg]

the conveyor has no ability to counteract the momentum produced by the engines because of the broken link caused by the wheels. because of this, a conveyor of any speed will only cause the wheels to spin faster, while the plane is unaffected

[orange]

Originally Posted by bdeg

the conveyor has no ability to counteract the momentum produced by the engines because of the broken link caused by the wheels. because of this, a conveyor of any speed will only cause the wheels to spin faster, while the plane is unaffected

I have no idea what you really mean. The plane's momentum is 0.

p = mv

The plane has no velocity. We start up the engines, energy drives the plane forward. It tries to move forward but it is in contact with the ground. The contact points are the wheels. Friction at the points of contact (i.e. where the rubber meets the road) resists any forward motion of the plane, basically pushing back. Since the contact points can't move forward the wheels spin so a new bit of wheel now contacts a new bit of road.

On the conveyor belt, the "road" also spins like the wheels. The new bit of road is in the same place as the first bit of road. There are now new contact points between new bits of wheel and new bits of road, but the position of these points relative to the surrounding ground is the same as the original position. The plane has not moved relative to the surrounding ground - and more importantly air. The plane's velocity remains 0. The plane's momentum remains 0. The energy that was spent spun the wheels and the conveyor belt.

Rinse and repeat.