Science Something amazing to tell you concerning physics and motion - Page 9

Jenson71 · 06-04-2009, 10:15 AM

This blows my mind.

Okay, say you have two ball bearings. You hold one in your hand and drop it. The other you put in a gun, point it straight forward, as level as the one in your hand, and pull the trigger, sending it hundreds of yards.

Which one lands first?

The one dropped in your hand right? RIGHT!?!?

No, actually they both hit the ground at the same time.

This is because the vertical component of motion is the same for both objects. They both fall vertically the same distance at about 10 meters per second squared (gravity, actually more like 9.8).

But Jenson, Jenson! What about the horizontal component of the gun-fired ball bearing? Actually, when air resistance is small enough to ignore as it is in this case (being that the bearings are exactly alike), the horizontal and vertical components of a projectile's velocity are completely independent of one another.

And, in this experiment, the gun-fired bearing is constantly falling from the moment it is fired. Yes, it looks like it is holding up in a straight line, but, it's actually falling and it's just hard to see with our eyes. And again, it is falling at exactly the same speed as the ball bearing you released in your hand -- the speed of gravity.

Post more cool science things in this thread.

I think I will later post Aristotle vs. Galileo and gravity, for a little history spin on science.

**Baby Lee** · 06-04-2009, 01:10 PM

Quote:

Originally Posted by bdeg

i don't even understand what you mean

that i'm being intentionally obnoxious?

doesn't matter. if everytime the plane moves forward 100 feet in a second, the treadmill moves back 100 feet per second, the plane will not take off.

The wheel is free spinning, absent a negligent kinetic friction coefficient, the plane's forward motion just makes the wheels spin faster.

damaticous · 06-04-2009, 01:13 PM

Quote:

Originally Posted by MagicHef

Heh...

What about this one:

The 747 would take off. It's the airspeed of the airplane not the groundspeed. Mythbusters did this one

**Buck** · 06-04-2009, 01:13 PM

Quote:

Originally Posted by MagicHef

Birds don't understand English. Ridiculous scenario.

Its okay to admit defeat.

MagicHef · 06-04-2009, 01:13 PM

Quote:

Originally Posted by Baby Lee

The wheel is free spinning, absent a negligent kinetic friction coefficient, the plane's forward motion just makes the wheels spin faster.

If it were a plausible scenario, the wheels and treadmill would each spin fast enough that the force from the friction in the wheel bearings would equal the force from the engines. Obviously this is not realistic, but this is what would happen if the treadmill exactly matched the speed of the wheels.

MagicHef · 06-04-2009, 01:14 PM

Quote:

Originally Posted by damaticous

The 747 would take off. It's the airspeed of the airplane not the groundspeed. Mythbusters did this one

Unless there's wind, the airspeed is the same as the groundspeed.

orange · 06-04-2009, 01:20 PM

The conveyor belt is not driven by any motor. It is simply free floating. As the wheels rotate, the belt rotates under them. All the energy is used pushing the belt. The plane isn't going anywhere.

If you've ever had an emissions test, you have seen this in practice.

The plane won't get airborne because with no forward motion, you have no air across the wings, hence no lift.

bdeg · 06-04-2009, 01:20 PM

i apologize, looking back i dont know how i believed it

i really need to think things through before i post
going to try to work on that

MagicHef · 06-04-2009, 01:21 PM

Quote:

Originally Posted by MediaCenterJunkie

Its okay to admit defeat.

Okay:

a) It's not the same scenario, as the mechanics of flight for a bird and a plane are very different, birds do not require air velocity over their wings to generate an upwards force.

b) There is no mechanism in this scenario that causes the rollerskates to have no velocity.

**cdcox** · 06-04-2009, 01:22 PM

Reversible mixing.

I saw this for the first time a few years ago and was amazed. Click on the video tab.

http://www.stevespanglerscience.com/...e-laminar-flow

bdeg · 06-04-2009, 01:24 PM

Quote:

Originally Posted by orange

The conveyor belt is not driven by any motor. It is simply free floating. As the wheels rotate, the belt rotates under them. All the energy is used pushing the belt. The plane isn't going anywhere.

If you've ever had an emissions test, you have seen this in practice.

The plane won't get airborne because with no forward motion, you have no air across the wings, hence no lift.

unless the plane's brakes are on it doesn't matter what force is applied to them

Silock · 06-04-2009, 01:26 PM

Quote:

Originally Posted by orange

The conveyor belt is not driven by any motor. It is simply free floating. As the wheels rotate, the belt rotates under them. All the energy is used pushing the belt. The plane isn't going anywhere.

If you've ever had an emissions test, you have seen this in practice.

The plane won't get airborne because with no forward motion, you have no air across the wings, hence no lift.

Ever seen an emissions test with a plane on a treadmill? Didn't think so.

orange · 06-04-2009, 01:28 PM

Quote:

Originally Posted by Silock

Ever seen an emissions test with a plane on a treadmill? Didn't think so.

No, but you see your car on a "treadmill" and it doesn't go anywhere - no matter that the speedometer says 60 mph.

MagicHef · 06-04-2009, 01:28 PM

It's a stupid question, and in the real world, such a treadmill would not exist, and the answer would be that it couldn't keep up with the plane, and the plane would take off. But, in a world where such a treadmill could exist, the plane would not move, and thus would not take off.

**Buck** · 06-04-2009, 01:31 PM

Orange, the difference here is that you are thinking of a car, which uses the wheels pushing off the ground to gain velocity and travel forward.

A plane on the otherhand, its wheels are not connected to anything other than barrings and they spin freely.

The plane doesn't use the ground to move forward, it uses the air.

orange · 06-04-2009, 01:33 PM

Quote:

Originally Posted by MediaCenterJunkie

Orange, the difference here is that you are thinking of a car, which uses the wheels pushing off the ground to gain velocity and travel forward.

A plane on the otherhand, its wheels are not connected to anything other than barrings and they spin freely.

The plane doesn't use the ground to move forward, it uses the air.

Sorry, all of it's energy is going to be directed to the treadmill, eliminating the plane's forward motion. Its energy from the engine pushes it forward. The friction between its wheels and the treadmill holds it back. All of that energy is transferred to the treadmill through the friction.

If the system is imperfect, you get some sort of wreck (the wheels come off, the treadmill breaks, etc.) but we're talking about a system that is functioning properly.

For the plane to move forward, the wheels have to move. If the wheels move, the treadmill moves under them and the plane goes nowhere.

06-04-2009, 10:15 AM
Jenson71 fides quaerens intellectum Join Date: Oct 2003 Location: United States Casino cash: $8330900	Something amazing to tell you concerning physics and motion This blows my mind. Okay, say you have two ball bearings. You hold one in your hand and drop it. The other you put in a gun, point it straight forward, as level as the one in your hand, and pull the trigger, sending it hundreds of yards. Which one lands first? The one dropped in your hand right? RIGHT!?!? No, actually they both hit the ground at the same time. This is because the vertical component of motion is the same for both objects. They both fall vertically the same distance at about 10 meters per second squared (gravity, actually more like 9.8). But Jenson, Jenson! What about the horizontal component of the gun-fired ball bearing? Actually, when air resistance is small enough to ignore as it is in this case (being that the bearings are exactly alike), the horizontal and vertical components of a projectile's velocity are completely independent of one another. And, in this experiment, the gun-fired bearing is constantly falling from the moment it is fired. Yes, it looks like it is holding up in a straight line, but, it's actually falling and it's just hard to see with our eyes. And again, it is falling at exactly the same speed as the ball bearing you released in your hand -- the speed of gravity. Post more cool science things in this thread. I think I will later post Aristotle vs. Galileo and gravity, for a little history spin on science.
Posts: 15,986

06-04-2009, 01:20 PM	#126
orange MVP Join Date: Sep 2000 Location: Denver, CO Casino cash: $10004900	The conveyor belt is not driven by any motor. It is simply free floating. As the wheels rotate, the belt rotates under them. All the energy is used pushing the belt. The plane isn't going anywhere. If you've ever had an emissions test, you have seen this in practice. The plane won't get airborne because with no forward motion, you have no air across the wings, hence no lift.
Posts: 11,661

06-04-2009, 01:20 PM	#127
bdeg Veteran Join Date: Aug 2006 Location: iowa Casino cash: $10004900	i apologize, looking back i dont know how i believed it i really need to think things through before i post going to try to work on that
Posts: 2,987

06-04-2009, 01:22 PM	#129
cdcox www.nfl-forecast.com Join Date: Sep 2000 Casino cash: $-478231	Reversible mixing. I saw this for the first time a few years ago and was amazed. Click on the video tab. http://www.stevespanglerscience.com/...e-laminar-flow
Posts: 46,032

06-04-2009, 01:28 PM	#133
MagicHef The Seated Villain Join Date: Apr 2007 Location: Seattle Casino cash: $560247	It's a stupid question, and in the real world, such a treadmill would not exist, and the answer would be that it couldn't keep up with the plane, and the plane would take off. But, in a world where such a treadmill could exist, the plane would not move, and thus would not take off. __________________ With a sack in 61% of his games, SB MVP Von Miller is the most consistent pass rusher in NFL history.
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06-04-2009, 01:31 PM	#134
Buck Take a Chill Pill Join Date: Nov 2006 Location: South Carolina Casino cash: $6180295	Orange, the difference here is that you are thinking of a car, which uses the wheels pushing off the ground to gain velocity and travel forward. A plane on the otherhand, its wheels are not connected to anything other than barrings and they spin freely. The plane doesn't use the ground to move forward, it uses the air.
Posts: 44,604