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.

[Radar Chief]

Originally Posted by damaticous

Actually, from what I remember, the ball bearing in your hand would hit the ground first.

when you fire a bullet from a gun the bullet tends to arch upward a bit, so it is actually falling at a different height from the one that is dropped.

I could be wrong, but I remember reading that or seeing it on TV or something.

Otherwise, yes, they'd hit the ground at the same time.

Not quite.
A bullet starts to drop the moment it leaves the barrel. Because of that the sites are adjusted so that the barrel is actually aimed higher that what the sites indicate so that the bullet “falls” into the target at the point predicted by the sites.
The sites are also aimed slightly to the right, IIRC, because the bullet comes out spinning and will move slightly from left to right as it travels.

[mikeyis4dcats.]

Originally Posted by orange

The bearing from the gun will land moments after the one you dropped. Unless the barrel of the gun has a length of 0. The barrel will prevent the bearing from falling until the bearing is out of the barrel.

the speed of a bullet traveling some 30 inches makes this negligible.

[Baby Lee]

Originally Posted by MediaCenterJunkie

3 friends go out to eat.

They get the bill and it is $25, but they don't really look at it too close.

They each give the waiter a $10 bill.

The Waiter decides since he cannot split $5 evenly among 3 people he decides to pocket $2, meaning the group paid a total of $27.

So the group paid $27 ($9 each), and he has $2 in his pocket, equaling $29.

What happened to the other dollar?

They only overpay the $2. The bill was $25, but they paid $27 [with the $2 pocketed]. 30-25=5, 3 to the customer, 2 to the waiter.

You're going the wrong way with the $2, it's the over payment for the $25 bill, not additional currency outside the $9 next from each. ie, 27-2=25, not 27+2=29 [an irrelevant sum].

[BigVE]

Dinner bill: $25

3 people gave $10 each for a total of $30.

Waiter automatically pockets $2. $30-$2=$28.

He gives each of the people $1 back meaning they actually paid $9 each for a total of $27.

The extra dollar? He took it. Dang thieves.

[sedated]

Originally Posted by MediaCenterJunkie

3 friends go out to eat.

They get the bill and it is $25, but they don't really look at it too close.

They each give the waiter a $10 bill.

The Waiter decides since he cannot split $5 evenly among 3 people he decides to pocket $2, meaning the group paid a total of $27.

So the group paid $27 ($9 each), and he has $2 in his pocket, equaling $29.

What happened to the other dollar?

There is no other dollar. The $27 ($9x3) includes the $2 the waiter took. The other $3 went back to the friends.

Am I missing something?

The second to last sentence is an illogical equation.

[orange]

Originally Posted by Jenson71

Count from the moment it leaves the barrel.

You can't. Because of the Heisenberg Uncertainty Principle, you can't know the bullet's exact position and its exact velocity at the same time.

Since the bullet "the moment it leaves the barrel" has a vertical velocity of 0, you can not know the instant that it actually begins to move downward. There will always be a margin of error.

[Buck]

Yeah it was a trick. You guys are too smart for it.

[Radar Chief]

Originally Posted by orange

The bearing from the gun will land moments after the one you dropped. Unless the barrel of the gun has a length of 0. The barrel will prevent the bearing from falling until the bearing is out of the barrel.

Good point, modify the theory to dropping the bearing at the same moment the other bearing leaves the rifle barrel.

[Baby Lee]

Originally Posted by Gonzo

WTF? Wouldn't the powder charge make a difference?

Let's say Im shooting a 10 mm ball bearing with about 55 grains of rifle powder.

I'm shooting this bearing from a height of 4 ft. I drop the bearing in my other hand at the same time from 4 ft. and the hit the ground at the same time...

Ok, now I adjust the powder charge to 75 grains. I shoot from the same height, but now I have adjusted the velocity of the projectile by about 800-1,000 feet per second. This would have to be a variable somehow.

Not if you shoot on the perfect horizontal, whatever impulse you have in the horizontal direction is irrelevant to the vertical force of gravity. More grains just means you go farther faster horizontally in as you fall at the same rate to the ground.

[Jenson71]

Originally Posted by orange

You can't. Because of the Heisenberg Uncertainty Principle, you can't know the bullet's exact position and it's exact velocity at the same time.

Dammit!!

My life has no more meaning.

[Baby Lee]

Originally Posted by T-post Tom

So if you're travelling at the speed of light in a spacecraft... and turn the headlights on...what happens? Answer me that Mr. Wisenheimer.

The light rays propigate forward at . . . . the speed of light.

[EyePod]

Originally Posted by Buehler445

You didn't know that? I learned that shit in my HS physics class. -9.8 m/s2 is stuck in my head for eternity.

WTF are they teaching you?
Posted via Mobile Device

I got accepted to college, then read the entire hitch hiker's guide to the galaxy series (i have a book that looks like a bible that contains all of the stories) instead of paying attention senior year in physics. Then I went to school for engineering, and I had to learn all the stuff that I should have learned in senior year during my freshman college year again. I was pissed that I didn't just pay attention during senior year of HS...

[Simply Red]

nerd alert!

boog out!

[Buck]

Another thing...wouldn't the mere action of observing either ball bearing affect the outcome????

[orange]

Originally Posted by MediaCenterJunkie

Another thing...wouldn't the mere action of observing either ball bearing affect the outcome????

That's where my answer in #36 comes in.