Only if the wheels were locked. And if that were the case, then the conveyor won't be moving because the plane's ground speed would be zero.

 

I'm sure quite a few - like when they told the Wright Brothers their plane wouldn't fly.

In this case, they are correct, the plane will fly.

Very entertaining show but not sure how huch I trust them. They did a story about whether you would get electrocuted if you peed on the electrified third rail of a subway track. The Myth Busters said you wouldn't. I work around electric third rail (600 VDC) all day and I am not risking my **** to find out they were wrong.

 

A swallow of what - ?

 

Whoever said the water in the lake won't rise when the boulder is pushed off a boat is making too many assumptions. Not enough info given to say one way or the other.

The boat's displacement of the lake water is only a function of the weight on the boat. The boulder's displacement once thrown overboard is a function of volume and not weight (assuming it doesn't float). So a large "boulder" of titanium might raise the lake water, while a small boulder of lead (of the same weight) might actually lower the lake water.

Thoughts?

 

My thought is you don't understand bouyancy. A boat will displace the EXACT same weight of water as the boat weighs. It will DISPLACE more water that the boat weights, that's what keeps it afloat.

No matter what the boulder is made of, it will displace the same volume of water as the submerged portion of the boulder. Thereby raising the level of the lake by that volume of water. Now practically speaking, it may not be possible to measure the rise in water level, but theoretically it can be calculated. IE add a volume of 1000 gallons to a 100 bazillion gallon lake the water might rise .003 angstroms.

Is this thread officially hijacked now?

 

What Is an Angstrom?
Electromagnetic radiation travels in waves. Scientists use the length of the wave (the distance between peaks) to define the energy of the radiation. Astronomers measure this length in "angstroms," a unit of measure equal to 1 hundred-millionth of a centimeter. It's a convenient shorthand to avoid writing lots of zeroes when talking about the wavelengths of light. In everyday terms, a sheet of paper is approximately 1,000,000 angstroms thick. Visible light covers the range from 4,000 to 8,000 angstroms

I didn't know and i think alot of others didn't know! i feel better as my brain level is up by 7 angstroms! Still want to know why anybody would want to put a plane on a conveyor?

 

I want to take a stab at reasoning this out.

First some basic physics:
1. Static friction is greater than sliding friction
2. Sliding friction is greader than rolling friction
3. Rolling friction is the lowest of the three listed here.

Some basic aeronautics:
Thrust - the force that moves a plane foward
Drag - the force that slows the plane down (is counter to thrust)
Lift - the force in the vertical direction
Gravity - the force toward earth (counter to lift)

First consider fact 1. No plane used in convetional passenger service today drives the landing gear wheels with any power whatsoever.

For the first takeoff the runway doesn't move and the plane has no landing gear. The fuselage is sitting on the ground. At this point all forces are equal to each other Thrust = Drag = 0, Lift = gravity The pilot applies full throttle to the engines which achieve maximum thrust. What happens? First the thrust has to overcome the drag created by static friction between the fuselage and the ground. If the thrust is greater than the drag, the plane starts to slide and the drag dropps off. Why? because sliding friction is less than static friction. If the plane can generate enough thrust to acheive takeoff speed then Lift > Gravity and the plane takes off. (Albeit severly damaged).

Next case, the plane has wheels. Why? Because rolling friction is much less than static and sliding friciton. Pilot applies thrust. What happens? Plane starts to move. Now the important question: What counter force (DRAG) does the runway apply to the plane? Very little because it is applying drag to the wheels which are free to turn. But how does the plane move? It's not applying turning force to the wheels. It moves forward because the thrust from the engines reacts against the stationary air behind the plane and pushes the plane forward. Or another way to put it, the engines create a low pressure area in front of the plane and a high pressure area behind the plane and this pushes the plane forward. When the plane achieves takeoff speed lift > gravity and the plane flies.

Now to the moving runway in this problem. The pilot applies full throttle. The engines create a low pressure are in front and a high pressure area behind the plane and thrust is generated. This thrust is acting on the still air around the plane, NOT on the wheels. As the force of thrust pushes the plane forward the conveyor starts moving. What does the conveyor act on? The wheels which are free to turn. How much drag does the conveyor impart to the plane? Nothing to the plane, only the wheels which are free to turn. Since the plane is applying thrust against the atmosphere and NOT the runway the plane starts to move forward relative to a stationary point on the ground. When takeoff airspeed is achieved, lift > gravity and the plane flies.

 

Just say the plane will fly because of magic and move on.

 

So will all the airports install conveyors, shorten the runways, and put casinos up?

We might be on to something here!

 

1. They already do. And for the love of god, if you're just going to stand there, move to the right, some of us want to pass you know.

2. Not after that tragedy I saw the other day in Chicago with the Southwest plane.

3. You can already gamble at the Las Vegas airport.

See how easy that was.

 

The conveyor belt doesn't shorten the distance required for the plane to take off... The plane still needs the same amount of room to pick up speed.

The casino in the Vegas airport is annoying enough. No need to expand that to the rest of the country!

 

If anyone still has a question of whether the plane will fly.

http://videos.streetfire.net/player....D-D6BA1A43A06B

 

What got me was the notion that conveyor would counter the _forward movement_ of the plane, which isn't the case, because the wheels don't make the plane move forward. In a car, yes, the forward movement would be negated by the conveyor.

Look at it this way, say the guy working the conveyor control is a little sleepy and the plane gets up to 10 mph before he kicks on the belt, so he turns on the belt and cranks it up to 10 mph the opposite direction. The only thing that is going to happen is the conveyor belt is going to make the tires spin at 20mph because the wheels are free turning and the plane will still be moving forward at 10mph.

 

This started off as a somewhat interesting debate---then I reached the end of the 1st page---and it's tuned ignorant. Sorry---not flaming anybody.

Think about it people, the thrust is going to propel the plane forward (doesn't matter what sort of plane)---which WILL create lift. It doesn't matter how fast the wheels are spinning---the wheels give the plane no motion.

The motion of the wheels is not what you would have to counteract to keep it from taking off---you would have to counteract the thrust of the engines.

The wheels are free rolling---their resistance makes no matter.

 

So far, you're the only one who thinks it will. I'm inclined to disagree with you, but not because everyone else does.

The plane needs airflow over the wings to create lift. If the plane is not moving relative to the air around it, no lift can be generated. As I understand the problem, the plane is not moving relative to the air around it.