Can a Plane on a Treadmill Take Off?

Actually, it is Newtonian relativity, but I'm not here to pick the flyspecks
out of the pepper.

Jim



No, this is strictly Galilean relativity (from four centuries ago);
Einstein's relativity has no bearing on this discussion.

--Gary

But to the guy inside, the train seems
stationary, while he himself is going at 5km/h and the guy outside to
him appears to be going backwards at 100km/h!
105km/h instead of 100!
Sorry, my mistake

Cecil Adams (world's smartest human being) is correct to a first
approximation. The correct answer to a second approximation is that it will
take off normally less some small correction factor for the increased
friction of the tires, wheels, and wheel bearings.

Note the "trick" of the question. It does not say that the conveyor keeps
the AIRPLANE at zero speed relative to the real world, just that it rotates
at a speed equal to the airplane moving forward. The question itself
supposes forward velocity of the aircraft relative to the earth and the only
thing the conveyor belt does is spin the wheels twice as fast.

Jim




"cjcampbell" wrote in message
oups.com...
Saw this question on "The Straight Dope" and I thought it was amusing.

http://www.straightdope.com/columns/060203.html

The question goes like this:

"An airplane on a runway sits on a conveyer belt that moves in the
opposite direction at exactly the speed that the airplane is moving
forward. Does the airplane take off?" (Assuming the tires hold out, of
course.)

Cecil Adams (world's smartest human being) says that it will take off
normally.

Sure, it's all connected to eachother. Einstein didn't invent
everything you know, he just used the tools and perfected them. This is
getting insane. Call it whatever you like. Happy now?
Byebye, I'm going flying now while you guys can continue the
discussion!
Have fun!

"RST Engineering" wrote in message
.. .
No, this is strictly Galilean relativity (from four centuries ago);
Einstein's relativity has no bearing on this discussion.

Actually, it is Newtonian relativity, but I'm not here to pick the
flyspecks out of the pepper.

Newtonian mechanics incorporates Galilean relativity.

--Gary

The whole problem is confusing because
"An airplane on a runway sits on a conveyer belt that moves in the
opposite direction at exactly the speed that the airplane is moving
forward."

Moving forward with respect to what? The conveyor belt? (you gt the
answer that it WONT take off), or the air? (you get the answer that it
WILL take off).

AMBIGUOUS!!!

(Cecil's answer assumes with respect to the air, and that is also how
he gets the tires going at twice the speed of the plane through the
air).

"Travis Marlatte" wrote in message
hlink.net...
Peter, I think you lost the relative perspective.

No, I didn't.

Given the original riddle, the treadmill only moves backward at the same
rate the plane moves forward.

The rate at which the treadmill moves is entirely irrelevant. An airplane
does not transmit any force through it's wheels. They simply rotate
whatever speed is required to account for whatever speed the airplane has
relative to the surface the wheels are in contact with.

It doesn't matter one bit WHAT speed the treadmill moves, according to the
original riddle or otherwise.

If the plane was developing exactly enough thrust to counteract the
headwind, it will not move and neither will the treadmill.

The headwind is just an example. The actual wind could be anything. Yes,
if the headwind is exactly the same speed as the airspeed, the airplane
won't move. My only reason for setting the headwind equal to airspeed, as
an academic point of reference, is that if it's not, the airplane isn't
going to stay sitting on the treadmill for very long, making the "riddle"
even less interesting.

Pete

"Kpi$LyLcEhRo" wrote in message
oups.com...
"Gary Drescher" wrote in message
...
"Kpi$LyLcEhRo" wrote in message
oups.com...
Actually this entire question and solution is about adding
and substracting velocity vectors and a perfect example of Einstein's
relativity theory.

No, this is strictly Galilean relativity (from four centuries ago);
Einstein's relativity has no bearing on this discussion.

I don't agree completely. But your right that Galilean blabla has to do
with this but [...]
So does Einstein! May I remind you of one of Einstein's
many mind experiments... The one about a train moving at a certain
speed, an observer inside the train walking to the front of the train
and an observer outside the train, standing still...

That's a classic thought experiment in support of Galilean relativity. Of
course Einstein was familiar with it, but it's part of a theory much older
than Einstein's.

Sure, it's all connected to eachother. Einstein didn't invent
everything you know, he just used the tools and perfected them.

Einstein invented quite a bit, including special and general relativity. But
those theories of relativity are not involved in the simple vector-addition
problem under discussion.

--Gary

"RST Engineering" wrote in message
.. .
Actually, it is Newtonian relativity,

Galileo: 1564-1642
Newton: 1643-1727

As Gary already noted, Newton's work built on Galileo's. The concepts here
were observed by Galileo.

but I'm not here to pick the flyspecks out of the pepper.

Uh, yeah, right. Sure you aren't.

"Morgans" wrote in message
...

"jesse" wrote in message
oups.com...
My friend and i were discussing this. There is not enough information
in the orginal question to determine anything.

I think jesse has earned his way into my "not worth the effort" file.
Anyone else have him strike you that way?

Jesse needs to learn how to capitalize, punctuate, and separate his
sentences into paragraphs in order to make his posts readable.