Science Something amazing to tell you concerning physics and motion - Page 7

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, 12:36 PM

Quote:

Originally Posted by bdeg

I believe the question was how fast does it need to be fired horizontally to enter orbit(maybe the phrase was 'escape gravity').

now that would be an impressive calculation(with wind resistance please)

That is the horizontal calculation [sans wr]. Like said above, at that speed, the curvature of the earth recedes under you at the same rate that gravity pulls you down to earth [that's why R-radius is integral to the equation].

MagicHef · 06-04-2009, 12:40 PM

Heh...

What about this one:

Quote:

Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?

bdeg · 06-04-2009, 12:42 PM

Oops, when the poster mentioned that Nasa had calculated it from the equator, and then i saw the angled diagram, I assumed it was being shot upwards. should've read more carefully.

I was actually envisioning a scenario where it broke out of the atmosphere and orbited there, but in this scenario it would orbit at the same height you shot it at. I wonder how long you'd have to move out of the way(upon thought, plenty).

Silock · 06-04-2009, 12:44 PM

In other news, the Earth is mostly round.

**Baby Lee** · 06-04-2009, 12:45 PM

Quote:

Originally Posted by MagicHef

Heh...

What about this one:

Well seeing as how the thrust comes from the jets, not the wheels.

MagicHef · 06-04-2009, 12:46 PM

Quote:

Originally Posted by Baby Lee

Well seeing as how the thrust comes from the jets, not the wheels.

If the treadmill moves at the exact opposite velocity of the wheels, how does the plane ever move?

**Baby Lee** · 06-04-2009, 12:47 PM

Quote:

Originally Posted by MagicHef

If the treadmill moves at the exact opposite velocity of the wheels, how does the plane ever move?

The wheels would spin at twice the rate of it's forward motion.

MagicHef · 06-04-2009, 12:49 PM

Quote:

Originally Posted by Baby Lee

The wheels would spin at twice the rate of it's forward motion.

The treadmill would still be spinning at the same speed as the wheels, making the speed of the plane zero.

bdeg · 06-04-2009, 12:50 PM

i think the answer you're looking for is no, because there isn't any air going over the wings

Silock · 06-04-2009, 12:52 PM

Are we seriously doing the plane on a treadmill thing? Only the trolls and complete idiots still think it won't fly.

**Baby Lee** · 06-04-2009, 12:52 PM

Quote:

Originally Posted by MagicHef

The treadmill would still be spinning at the same speed as the wheels, making the speed of the plane zero.

You don't gain momentum in a jet by pushing the pavement below you backward, you push the atmosphere behind you backwards.

Unless that treadmill can manipulate the atmosphere, it's irrelevant.

MagicHef · 06-04-2009, 12:53 PM

The answer is actually that it's an impossible scenario, but I believe that if it were possible, the plane would not take off.

bdeg · 06-04-2009, 12:55 PM

Quote:

Originally Posted by Silock

Are we seriously doing the plane on a treadmill thing? Only the trolls and complete idiots still think it won't fly.

explain to me how it will get off the ground if it can't accelerate in relation to the air

MagicHef · 06-04-2009, 12:57 PM

Quote:

Originally Posted by Baby Lee

You don't gain momentum in a jet by pushing the pavement below you backward, you push the atmosphere behind you backwards.

Unless that treadmill can manipulate the atmosphere, it's irrelevant.

The treadmill is not irrelevant. If the speed between the base of the treadmill and the ground is zero, the speed between the wheel hubs and plane is zero, and the speed of the treadmill is equal to the negative speed of the wheels, the speed of the plane must be equal to the speed of the ground.

JuicesFlowing · 06-04-2009, 12:58 PM

Fill a bottle with water. Put a card on the top as a cover. Hold onto the card while turning the bottle of water upside down. Let go of the card. The water will not pour out of the bottle, the card will hold it all in! I learned that from watching Mr. Wizard!!!!!!!

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, 12:42 PM	#93
bdeg Veteran Join Date: Aug 2006 Location: iowa Casino cash: $10004900	Oops, when the poster mentioned that Nasa had calculated it from the equator, and then i saw the angled diagram, I assumed it was being shot upwards. should've read more carefully. I was actually envisioning a scenario where it broke out of the atmosphere and orbited there, but in this scenario it would orbit at the same height you shot it at. I wonder how long you'd have to move out of the way(upon thought, plenty).
Posts: 2,987

06-04-2009, 12:44 PM	#94
Silock MVP Join Date: Dec 2006 Location: Overland Park Casino cash: $10020882	In other news, the Earth is mostly round.
Posts: 19,908

06-04-2009, 12:50 PM	#99
bdeg Veteran Join Date: Aug 2006 Location: iowa Casino cash: $10004900	i think the answer you're looking for is no, because there isn't any air going over the wings
Posts: 2,987

06-04-2009, 12:52 PM	#100
Silock MVP Join Date: Dec 2006 Location: Overland Park Casino cash: $10020882	Are we seriously doing the plane on a treadmill thing? Only the trolls and complete idiots still think it won't fly.
Posts: 19,908

06-04-2009, 12:53 PM	#102
MagicHef The Seated Villain Join Date: Apr 2007 Location: Seattle Casino cash: $560247	The answer is actually that it's an impossible scenario, but I believe that if it were possible, the plane 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.
Posts: 10,753

06-04-2009, 12:58 PM	#105
JuicesFlowing Losing with passion. Join Date: Sep 2007 Location: Oblivion Casino cash: $10004925	Fill a bottle with water. Put a card on the top as a cover. Hold onto the card while turning the bottle of water upside down. Let go of the card. The water will not pour out of the bottle, the card will hold it all in! I learned that from watching Mr. Wizard!!!!!!!
Posts: 4,399