The fact is that no matter how fast the treadmill is going it won't keep the plane or skateboard still when the rope is pulled or the jets kick in. It's not possible.

1876 - so the treadmill would have to speed up to match the forward thrust of the plane, which it can do up to the time that the wheels leave the conveyor.

You running on a treadmill is completely different. Your only force is generated by the contact patch between your foot and the treadmill. The plane has a force external to the tires and treadmill to generate forward motion. Indeed, the wheels are there to mitigate the ground/treadmill impact on forward motion. Put a jet on your skateboard, it will move forward against the best efforts of the treadmill because its ability to impact the forward progress is mitigated by the wheels.

AggieQ - no reason to be unfriendly about it.

quote:

---

1876er

If I run faster on the treadmill, I must increase the speed of the treadmill to prevent myself from running through the wall in front of the treadmill.

---

I don't know why you would think running on a treadmill would have anything to do with the airplane or skateboard.

Strap on some rollerblades and ride the treadmill tonight for a couple of hours and see if that helps you understand the concept a little better.

It flies as long as there is acceleration. I made a dumb assumption that V would be constant in teh beginning. Plane flies.

oh. my. god. Ok for the last time, there is no correlation between you "running" on a treadmill and a skateboard "rolling" on the treadmill attached to a rope. Just like there is no correlation between a plane "rolling" on the conveyor and a car "driving" on the conveyor. The car's forward momentum is derived from a force exertion of the wheels on the surface: the plane's forward momentum is derived from the thrust from the engines.

To make your analogy more accurate, and for your sake I would recommend actually conducting this experiment:

Go put on roller skates (or roller blades, whatever)

Stand on a treadmill

Tie a rope to the handle bars

Grab the rope

Now, speed the treadmill up really fast. Obviously you aren't going anywhere cause you are holding on to the rope, right? Now, pull yourself forward. You move forward. AND YOU WILL MOVE FORWARD NO MATTER WHAT THE SPEED OF THE TREADMILL IS. This is even more true of the treadmill is only going the speed you are pulling yourself. If you can pull yourself forward when the treadmill is going really fast, then you can pull yourself forward when it is going much slower, say, at the speed you are pulling yourself.

If you don't see this then you are just plain ignorant.

Now, apply this to the plane. You pulling on the rope is an analogy to the thrust of the plane. Your wheels on the treadmill are an analogy to the wheels of the plane on the conveyor (almost the exact same case). When you pull, you go forward, no matter what the speed of the treadmill is doing. Thus, when the plane turns on it's engines, it is "thrusting" forward (think of it as a plane pulling on a big rope in front of it) and it moves forward, no matter what the speed of the conveyor. Forward motion relative to the air will eventually create lift


The plane takes off.

sorry to be a little cross, I just finished in the last 6 days 4 aerospace engineering finals, I think I will go take a nap now.

Plane flies...

Tie yourself to something and let the treadmill and rollerblades generate a little tension on the rope. Roll there until the broccoli, cabbage, and chili burrito con carne you had for dinner runs its course. Ignite the pressurized methane emmission and notice a reduction in the tension on the rope. Now imagine if you had 4 stomachs like a cow.

Real world physics doesn't have to be boring!

cool. hey man I used some harsh words in my last few posts, I really am too tired to be posting on texags right now methinks, forgive me?

dangit whoop, now I am just hungry!

yeah, a nap sounds like a good idea AggieQ. Hell, I might as well have one, too, and I haven't been taking finals, just getting old.

haha, alright guys, have a great day. gig 'em

The damn plane flies...

The pen is blue! The pen is blue! The G- D- pen IS BLUE!

'Q apologized, '76er. How about a few stanzas of Cum Bah Yah, fellas? Besides, who can still be pissed after my "pressurized methane emission" post?

[This message has been edited by WHOOP!'91 (edited 12/13/2006 1:25p).]