Tell me about gravity.

**Sandform** · 01-08-2008 01:43 AM

This is really just a basic question.

Objects are supposed to fall at the same speed no matter what if there is no air resistance on a planet.

But the objects themselves have an attraction of their own don't they.

So is the attraction just so minuscule people don't bother mentioning it when they explain the theory of gravity in relevance to a vacuum?

**Sandform** · 01-08-2008 01:53 AM

I may have answered my own question hehe.

...........................2
MaA = -G Ma ME / RE

Mass cancels out hehe.

**CoLd BlooDed** · 01-09-2008 03:59 AM

Gravity makes things go down.

**slayer** · 01-09-2008 04:08 AM

If anything falls...blame gravity.

I didn't drop the statue of liberty! Gravity did!

**Replicon** · 01-09-2008 05:08 AM

To answer your question, there is a parallel between electric fields and gravitational fields. The force between two point masses (or spheres) is: G*m1*m2/r^2, where r is the distance between the points and G is the gravitational constant (see http://en.wikipedia.org/wiki/Gravitational_force ).

When they teach you in physics 101 that "g" is the constant acceleration with which objects fall, what they're not telling you is that the distance covered by an object falling a few feet is so small that "g" can basically be considered constant.

Also, just to be nitpicky:

Objects are supposed to fall at the same speed no matter what if there is no air resistance on a planet.

By speed, you really mean acceleration, of course?

**blade5x** · 01-09-2008 05:22 AM

MaA = -G Ma ME / RE

This equation is only valid when Ma is being treated as a point mass. The effect is negligible compared to the large mass.

The Newtonian equations are just good estimates of what we perceive as "gravitational force", when gravity is not really a force, but a bending of space-time. So the physics you learn in high school... not exactly 100% right - but close enough. You won't notice the errors in the equations (when compared to observation) until you reach astronomical scales.

**jacobo** · 01-09-2008 05:24 AM

Originally Posted by CoLd BlooDed

Gravity makes things go down.

i concur wholeheartedly with this conclusion

**Spartiate** · 01-09-2008 05:45 AM

Originally Posted by jacobo

i concur wholeheartedly with this conclusion

High tide is water being pulled upwards by the Sun's/Moon's gravity.

**CoLd BlooDed** · 01-09-2008 06:09 AM

But that's being pulled towards them, which is basically down once you think about it.

**♥Mark** · 01-09-2008 06:14 AM

Originally Posted by CoLd BlooDed

But that's being pulled towards them, which is basically down once you think about it.

Whoa. It's like my whole world has been turned on its head.

**arby** · 01-09-2008 06:18 AM

Now, this is a story all about how
My life got flipped-turned upside down
And I liked to take a minute
Just sit right there
I'll tell you how I became the prince of a town called Bel Air

**CoLd BlooDed** · 01-09-2008 06:28 AM

Originally Posted by Mark75

Whoa. It's like my whole world has been turned on its head.

Dude, I know! I just like, totally proved that up is down, and down is up!

**♥Mark** · 01-09-2008 06:47 AM

Whoops, I think I ruined the thread again.

**Sandform** · 01-09-2008 12:02 PM

Originally Posted by Replicon

By speed, you really mean acceleration, of course?

Yes I did mean acceleration. All though technically, acceleration is just the change in speed...so at any given moment they are also traveling the same speed =P

I came to the conclusion that when your comparing the two items against each other, the masses cancel out because there are two different masses. Thus the Earth falls towards the feather at a different speed, which could be found by switching the equation around so that the Earths mass is negated from the equation, and thus there would be the speed at which the earth is falling towards the feather, which is accurate, at any given point. In other words, it is only accurate for the specific moment and distance you are starting the equation, and there is probably another formula I haven't learned about that describes the average speed that exists during the whole distance traveled.

Phew that was a lot of talking lol. Lemme know if my conclusion is right anyone who reads it and knows X.X.

**Riot Maker** · 01-10-2008 05:23 AM

gravity is the only thing holding us back.

think about that and digest it. Regurgitate it after then tell me how you feel.

**Abra** · 01-13-2008 04:38 AM

Now the real question is why gravity exists. Yes, we all know that the more mass an object has, the more gravitational force it exherts. But why?

**Spartiate** · 01-13-2008 05:13 AM

Originally Posted by Abra

Now the real question is why gravity exists. Yes, we all know that the more mass an object has, the more gravitational force it exherts. But why?

Why must there be a why? Science deals in hows.

**♥Mark** · 01-13-2008 05:24 AM

Then read the question as "how did it come to be like that in the first place?"

**Sornaensis** · 01-13-2008 05:25 AM

Ooh, Ooh, PICK ME! I KNOW!

Because the universe would suck more than it already does if nothing stayed down

.

**Spartiate** · 01-13-2008 05:25 AM

Originally Posted by Mark75

Then read the question as "how did it come to be like that in the first place?"

God did it.

**Sornaensis** · 01-13-2008 05:27 AM

Originally Posted by Spartiate

God did it.

Atheism because banana.

**♥Mark** · 01-13-2008 05:47 AM

You have it backwards.

**Sandform** · 01-13-2008 09:39 AM

Originally Posted by Abra

Now the real question is why gravity exists. Yes, we all know that the more mass an object has, the more gravitational force it exherts. But why?

I heard it was because matter bends space...or something like that.

All the forces get pushed into the line headed towards the center of the mass. Like...if you throw a ball...but suddenly the line it was in starts to curve.

Of course I don't remember everything, this could be some theory that has been long since abandoned.