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.

Don't spit into the wind.

Neeeeeeeeeeeeeeeeeeerrrrrrrrrrrrrrrd!!!


:)





Thats pretty interesting though...

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?
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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.

Everything I was taught in high school physics I also forgot the very same day. I was a horrible, horrible high school student and I feel bad about it these days.

Oh, ah... we're discussing a perfect gun that does not send a bullet upward at all.

But yeah, that would screw it up.

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?

O I C;)

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. :)

Taxes or tip.

We haven't gotten that far yet.

Awww, come on guys, it's so simple maybe you need a refresher course. It's all ball bearings nowadays. Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads, and I'm gonna need 'bout ten quarts of anti-freeze, preferably Prestone. No, no make that Quaker State.

I thought this at first, but as the bullet spins, it will create pressure differences (high or Low which creates lift) equal to all sides, which will cancel out any lift/gravity change. Only outside forces, such as updrafts and downdrafts will effect it's decent rate.

Nice Fletch quote.

If he pocketed $2 they paid $28.

What if you shoot it into a Mountain? Then it will hit the ground first.

Oh, and we're in a vacuum.

While that makes sense, how do you explain the fact that they each paid $9? That equals $27.

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.

Oh I KNOW!!

You say they paid $27, and then add $2 which is already part of the $27. You shouldn't be adding that $2. Thus, it's only $27. So there are three dollars, which the waiter gives back to the people. It's deceptively written.

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.

I'm saying the math in your problem is incorrect. If he pocketed $3, then they would have each paid $9. But it says he pocketed $2 which makes it $27...which is bad math.

Apparently it went to the California Public School system because it didn't teach the students how to properly read and/or analyze word problems.

You are overthinking it!!!!!
$30-$2 is NOT $27!!

Count from the moment it leaves the barrel.

I'm just stretching it out for complete explanation.

how many gallons are in a 5 gallon bucket?

None, until you fill it.

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.

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

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].

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.

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.

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. ;)

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

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

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.

Dammit!!

My life has no more meaning.

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

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...

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

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

No way.

Here's a good one that those who know, know. And those who don't it's as obtuse as **** to figure.

If you plug the horizontal velocity into the quadratic formul ie -b+/-sqrtb^-4ac/2a, you get two values, one positive and one negative.

What's the significance of the negative value.

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.

Yep. :clap:

Time zone.
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Because the one in the mountains is traveling slightly faster then the one at sea level. The faster an object travels, the more time "slows down" for it.

Gave me a headache.

i'm referring to rate. as in, one clock will be slower

For the n00bs

http://trevorpythag.files.wordpress..../02/qdrtc2.gif

yeah too easy

Interesting. That makes sense.

Most of us have something on our person that proves the Theory of Relativity, what is it?

This has now passed the surprising success of my last science and math thread: http://chiefsplanet.com/BB/showthread.php?t=201648

uno ansr?

Still cool to think about though. Growing up I had a theory that if a person where to travel faster then light away from the Earth, that person would be able to turn around and watch "time" travel backwards on Earth. When I learned that light travels at the same speed relative to the person, it crapped all over my theory LOL.

Atmopheric pressure?

Actually, Jenson is correct.

Actually, if the bullet is fired horizontally at a fast enough speed, it will NEVER hit the ground. Why? Because it is now in orbit and constantly falling.

nope, time dilation as notorious referred to

lithium ion battery?

Other way around 3x10=30, 30-3=27=3x9. The 2 is the difference between the 25 billed and the 27 paid.

And what would speed would the bullet need to travel to escape Earth's gravitational pull?!?!?!?! :)

This reminds me of those hilarious exam answers.

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

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?

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?
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Very good, at the equator. Those NASA guys are pretty smart, aren't they?

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.


[edit] Okay, I get it.

http://upload.wikimedia.org/wikipedi...Cannon.svg.png

When riding in the back seat of a car, and your buddy pisses out of the front passenger window, make sure your window is rolled up.

So, you're assuming the Earth is flat here?

Because I reset all of the clocks on daylight savings.

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

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.

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

Damn Farmers. :)

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.