Weird scientific questions

[Kszchroink]

My friends and I got into some heated arguments about these questions, so I decided to share them with SF to see what you guys think:

• Imagine an airplane standing on a gigantic treadmill. The plane is taking off, but the treadmill is moving in the opposite direction at the exact same speed. Would it still be able to lift off?
• Is 0.999... equal to 1?
• What would you consider to be a "big midget"? Where is the line between a big midget and a small person?

[Dascoo]

1. Stupid question. Of course the plane can't take off, it's not generating any lift.

2.  Apparently 0.99999999 and ongoing equals 1.

3. Even dumber question.

[frogboy]

Actually, since the plane is moving at a forward velocity relative to the treadmill it generates lift from the treadmill.

Also, I'm pretty sure midgets turn into short people at around 145 centimetres tall.

[{LAW} Gamer_2k4]

Actually, since the plane is moving at a forward velocity relative to the treadmill it generates lift from the treadmill.

Not so.  Lift is generated from the air flow over the wings, and if there's no air flow (because the plane isn't moving), there will be no lift.  It's the same reason you feel the wind through your air when you're biking on a trail, but you don't when you're on a stationary bike.

[frogboy]

You do when you're on a bike on a treadmill though.

[{LAW} Gamer_2k4]

My friends and I got into some heated arguments about these questions, so I decided to share them with SF to see what you guys think:

• Is 0.999... equal to 1?

Yes and no.  It's like asking what 0⁰ is.  Zero to any power is zero, but any number to the zeroth power is one.

The simplest proof for your question is as follows:
1/3 = .333...
3 * 1/3 = 3 * .333...
1 = .999...

The simplest refutation for that claim is that 1 - .999... = .0000...01.

Date Posted: October 05, 2007, 09:19:36 am

You do when you're on a bike on a treadmill though.

Nonsense.  If the air is still, then the only thing you'd feel is its speed relative to yours.  So if you don't move, then neither does the air (relative to you).  Could you please explain why you believe this changes based on the device you're on?

[frogboy]

It can be measured empirically.

[{LAW} Gamer_2k4]

I choose to doubt that.  If you can't explain it, can you link me to empirical evidence that does?

[Kszchroink]

I choose to doubt that.  If you can't explain it, can you link me to empirical evidence that does?

Wait here for a moment whilst I fetch some icecreams.

[frogboy]

I choose to doubt that.  If you can't explain it, can you link me to empirical evidence that does?

Surely it's the same evidence which states that the sky is blue, or that objects fall towards a large mass. In the information age, we don't need scientific papers on the most trivial of observations.

[{LAW} Gamer_2k4]

I choose to doubt that.  If you can't explain it, can you link me to empirical evidence that does?

Surely it's the same evidence which states that the sky is blue, or that objects fall towards a large mass.

Trivial, eh?  Let me try to put this trivially.

If you're on a treadmill, you remain still.  No matter what device you're riding, you remain still.  You have no motion relative to your surroundings, whether you're on a bike or on foot.  No relative motion at all.  That means you're basically standing still.  Does the air sense that you're on a bike and decide to blow against you? Or if you're in a plane and have no relative motion, does the air think, "Hey, this is a plane that's moving.  Despite the fact that I wouldn't move against a plane in the hangar, the fact that its wheels are turning changes all of this!"

Don't be ridiculous.

In the information age, we don't need scientific papers on the most trivial of observations.

The point of the information age is that we have easy access to the scientific papers, not that we can ignore them because they exist somewhere and we can't be bothered to find them.

[frogboy]

And what makes you think that air can't be placed on a treadmill? It's moving backwards as well; there's your air current. Frankly, I don't see why you're overcomplicating the matter with absurd ideas such as air which is sentient.

[Rook_PL]

Excuse me, but I see this way: plane has propellers. They are forcing the air to move in certain direction, if the forced air is fast enough, the wings generate aerodynamic lift strong enough to lift the plane itself (if the air speed is to low the plane stalls). It doesn't matter if the ground (or treadmill) is moving in relation to plane.
I saw birds (in laboratory) flying in wind generated by big fan. They were actually stationary in relation to viewer, but waving their wings and so.
I think it's possible only theoretically for such plane to lift off.

[Aquarius]

I think the airplane wheels would move 2x faster but everything else would look normal and it would lift off without a problem.

[{LAW} Gamer_2k4]

Frankly, I don't see why you're overcomplicating the matter with absurd ideas such as air which is sentient.

Because you implied that air reacts differently to someone running than to someone on a bike.

Excuse me, but I see this way: plane has propellers. They are forcing the air to move in certain direction, if the forced air is fast enough, the wings generate aerodynamic lift strong enough to lift the plane itself (if the air speed is to low the plane stalls). It doesn't matter if the ground (or treadmill) is moving in relation to plane. So it IS possible.
BUT
If there is no wind, It's hard for me to imagine so powerful engines, and so fast-moving treadmill.

Well, my scenario always involved a jumbo jet, with turbofans under the wings.  These provide thrust, causing forward motion and consequently generating a relative air flow over the wings.  The air flow wouldn't exist without the forward motion.

However, if a plane had a propeller, it would be a slightly different case, since the propeller is generating some of the airflow itself.

I think the airplane wheels would move 2x faster but everything else would look normal and it would lift off without a problem.

That implies that the plane is moving forward.  The point of the question is that the airplane has no forward motion at all.

[Serial K!ller]

Excuse me, but I see this way: plane has propellers. They are forcing the air to move in certain direction, if the forced air is fast enough, the wings generate aerodynamic lift strong enough to lift the plane itself (if the air speed is to low the plane stalls). It doesn't matter if the ground (or treadmill) is moving in relation to plane. So it IS possible.
BUT
If there is no wind, It's hard for me to imagine so powerful engines, and so fast-moving treadmill.

But the propellers are there to generate propulsion not to directly generate airflow for the wings, the air wouldn't pass everywhere on the wings only behind the propellers not on the entire length of the wing so that wouldn't be enough for an ordinary plane.

and I agree with {LAW} Gamer_2k4 I think that there won't be any lift

[Dascoo]

Excuse me, but I see this way: plane has propellers. They are forcing the air to move in certain direction, if the forced air is fast enough, the wings generate aerodynamic lift strong enough to lift the plane itself (if the air speed is to low the plane stalls). It doesn't matter if the ground (or treadmill) is moving in relation to plane.
I saw birds (in laboratory) flying in wind generated by big fan. They were actually stationary in relation to viewer, but waving their wings and so.
I think it's possible only theoretically for such plane to lift off.

*facepalm*

Of course anything with enough thrust can become airborne...

I seriously hope you're trolling. You to frogboy.

[Serial K!ller]

I got a question what would happen to the airplane if instead on a treadmill it was inside a moving train (opposite direction same speed)

[{LAW} Gamer_2k4]

I got a question what would happen to the airplane if instead on a treadmill it was inside a moving train (opposite direction same speed)

The exact same thing.  The plane still has no net motion, so no lift is generated.

EDIT: Actually, I'm not sure.  After all, the air inside the train would be moving with the train.

[Smegma]

First off, it wouldn't FIT in a train.