Something amazing to tell you concerning physics and motion

[Jenson71]

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.

[Rain Man]

Originally Posted by nstygma

explain why two identical atomic clocks will not read the exact same time after a year if one is at sea level and the other is elevated, say, in denver.

Because I reset all of the clocks on daylight savings.

[notorious]

Originally Posted by Buehler445

Dude. WTF. I know -9.8m/s2. That's pretty basic shit.

Why the **** do you know the speed required to escape earth's gravity?
Posted via Mobile Device

It all depends on where/what direction you are launching.

[Baby Lee]

Originally Posted by MediaCenterJunkie

Oh and Baby Lee, to answer your question about the Quadratic formula,

The negative answer probably has to do with what direction you are facing. If you are standing at 0 and everything in front of you is a positive direction (in feet) 1 foot, 2 feet, etc. and everything behind you is negative (feet) -1, -2, etc. then the negative answer for that would be how far it goes behind you???

My english isn't very good in the above sentence, hopefully that makes sense and is the correct answer?

Surprisingly close. It's the spot behind you where, if the bullet hadn't been fired from a gun but were simply traveling at the velocity in perpetuity, the bullet would have emerged from the surface of the earth. ie, you exerted a force on the bullet to raise it from the ground to the level it is at when you fire it. That force would take the form of a vertical velocity [that peaked and turned back downwards d/t the counterforce of gravity at the level of the gun barrell] in a perpetual horizontal velocity object.

[notorious]

Originally Posted by Rain Man

Because I reset all of the clocks on daylight savings.

Why we still change our clocks for daylight savings time confuses me more then the realtionship between time/space.

Damn Farmers.

[Baby Lee]

Originally Posted by orange

I'm sorry, I'm not seeing it. The bullet is fired tangentially to gravity. It has no vertical momentum away from the Earth's gravitational pull. It will simply continue to orbit at the same height.

It's not moving away from the earth, it's orbiting [the earth is receding from it due to it being a ball and all, but that receding is equalled by the pull of gravity], Of course this would only work this close to the earth in a vacuum as air resistance would slow it pert quick.

[Buck]

Originally Posted by Baby Lee

Surprisingly close. It's the spot behind you where, if the bullet hadn't been fired from a gun but were simply traveling at the velocity in perpetuity, the bullet would have emerged from the surface of the earth. ie, you exerted a force on the bullet to raise it from the ground to the level it is at when you fire it. That force would take the form of a vertical velocity [that peaked and turned back downwards d/t the counterforce of gravity at the level of the gun barrell] in a perpetual horizontal velocity object.

You lost me.

[orange]

Originally Posted by Baby Lee

It's not moving away from the earth, it's orbiting [the earth is receding from it due to it being a ball and all, but that receding is equalled by the pull of gravity], Of course this would only work this close to the earth in a vacuum as air resistance would slow it pert quick.

Its orbit spreads out to a parabola, so in effect it never "returns" to its origin. (looked it up, of course).

[orange]

Now somebody explain this. Sometimes I'll post a message on this forum, and when it posts - which should refresh the page - it will show my message in position x. Then when I come back - refreshing the page again - it will show the same message in position x + y with new messages that were posted before mine but not shown.

????

[Buehler445]

Originally Posted by orange

Now somebody explain this. Sometimes I'll post a message on this forum, and when it posts - which should refresh the page - it will show my message in position x. Then when I come back - refreshing the page again - it will show the same message in position x + y with new messages that were posted before mine but not shown.

????

You cheer for the Donkos.
Posted via Mobile Device

[Buck]

Originally Posted by orange

Now somebody explain this. Sometimes I'll post a message on this forum, and when it posts - which should refresh the page - it will show my message in position x. Then when I come back - refreshing the page again - it will show the same message in position x + y with new messages that were posted before mine but not shown.

????

This should clear things up

http://fetchback.typepad.com/.a/6a00...1faa970b-800wi

[Baby Lee]

Originally Posted by MediaCenterJunkie

You lost me.

You get that it took a force to get the bullet from the surface of the earth to the place it is in the chamber of the gun propped against your shoulder.

You get that when you fire the gun, the bullet has initally no vertical momentum and a horizontal momentum dictated by the power of the powder. And that immediately thereafter it has a vertical momentum down dictated by gravity.

Now imagine that you were on the ground and tossed a free bullet to exactly the level of the bullet in the gun, whereupon it stop midair for an instant and then would return to earth.

The negative solution represents the place behind you that a bullet with the horizontal momentum equal to that of the gunfired bullet, and a vertical momentum equal to that toss from the ground, would have to be 'tossed' for it to traverse the exact same arc as the fired bullet.

[orange]

Originally Posted by MediaCenterJunkie

This should clear things up

http://fetchback.typepad.com/.a/6a00...1faa970b-800wi

That did it. It all makes sense now.

[Buck]

Originally Posted by Baby Lee

You get that it took a force to get the bullet from the surface of the earth to the place it is in the chamber of the gun propped against your shoulder.

You get that when you fire the gun, the bullet has initally no vertical momentum and a horizontal momentum dictated by the power of the powder. And that immediately thereafter it has a vertical momentum down dictated by gravity.

Now imagine that you were on the ground and tossed a free bullet to exactly the level of the bullet in the gun, whereupon it stop midair for an instant and then would return to earth.

The negative solution represents the place behind you that a bullet with the horizontal momentum equal to that of the gunfired bullet, and a vertical momentum equal to that toss from the ground, would have to be 'tossed' for it to traverse the exact same arc as the fired bullet.

Thanks

[Fish]

Originally Posted by orange

Now somebody explain this. Sometimes I'll post a message on this forum, and when it posts - which should refresh the page - it will show my message in position x. Then when I come back - refreshing the page again - it will show the same message in position x + y with new messages that were posted before mine but not shown.

????

You need the Divide by Zero Firefox plugin....

[bdeg]

Originally Posted by Baby Lee

11.186 km/s. More precisely sqrt(2GM/R), where G-gravity, M-mass, R-radius.

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)