Question

Does every object have a small amount of gravitational pull or does it have to go over some kind of "bar" to have that?

Answer 1

I'm afraid of getting into answering that question :D. In classical physics there is no problem with that question. Looking at a gravitational force equation I would say that anything with mass has gravitational pull (but thats not physics, thats math :D). But, as we know, classical physics is wrong and I don't know that much about QED or QCD for that matter to even try to answer something like that. Also the thing is that we, as human kind, still don't know how gravitational force works so... hopefully someone will be more helpful. I'm very interested in this question.

Answer 2

Every single tangible mass attracts every other single mass. Although you'll likely learn the concept and things such as the formula for gravitational force in classical physics or classical mechanics, it's not limited to just introductory studies but rather an accepted principle of mass; it's how stars and planets were first born. But as the distance between the masses increase, the attractive force decreases (exponentially according to the formula); a mass such as the sun, which although obviously the most massive object in our solar system, and although it keeps our planet in orbit, doesn't suck people off the Earth because of how far away it is, meaning the Earth's mass is sufficient to draw nearby masses to it. It's not yet understood WHY mass has this bizarre property, but it's a theory yet to be disproved; everything from stars to quarks appear to exhibit it.

Answer 3

Inopeki is 14 years old, that's right isn't it? So as far as everything every day go, everything has gravity.

At a quantum level it's not exactly clear what's going on; this is in part what the experiments currently going on in CERN are trying to ascertain--"How does gravity work at a quantum level? Is there a field (called the Higgs Field) that provides a sort of quantum slurry that acts as gravity? Are there particles that convey gravitational force, Higgs Bosons?" (The press loves sensation and called the Higgs Boson the 'God Particle')

The short answer is we don't know exactly what the minimum mass is for gravity to work. But whatever it is, it's almost certainly less than the mass/energy of hydrogen atom.

In any world, that's still a very, very small number.

Answer 4

ah, thank you for the answers guys. I know he is 14, well now I do, but I still think it would be better to say we just don't know. No cheating, just the way it is...:D :D

Answer 5

Please dont take my age into what answer you will give me, but i have a few questions on that.
-If you have a boat on the ground that weighs 500kg, it has about 5000 newton of force toward the center of earth, right? What if the minimum mass for having a gravitational pull is lets say 5000kg, would a boat that weighed that much maybe have 50001 newton because it pulls earth towards it? I think you can measure this if you have an object with enough mass.
-I have heard about CERNs "hadron supercollider", what exactly does it do and what are they trying to find through their experiments?
-What is a quark?
-Can you explain the higgs field in a little more detail?

Answer 6

Gogind, physics is inductive; in physics we conduct experiments and inductively reason from specific instances to general principles. So we can never "know" that a principle or law of physics is true as we can a mathematical principle (which is a deductive science), but we can have various levels of confidence in physical theories.

As a phenomenon is verified again and again and withstands all experiments and trials, it is usually elevated from "theory" to "principle" to "law." Gravity is one of the most time-tested physical phenomena of all time, and so we can say with a very high level of confidence that it is in all cases true - keeping in mind that it is inductively derived, of course.

As fewscrewsmissing noted, there have so far been no "exceptions" to the law of gravity that would make us doubt its universality.

Answer 7

Inopeki,

As far as we know, all masses have a gravitational pull. You, for example, have a graviational pull on the earth; you are actually pulling the earth toward you, just as the earth is pulling you toward it.

The reason the earth does not noticeably accelerate toward you when you leave the surface of the earth is that your gravitational pull is negligible compared to the earth's gravitational pull. You can calculate your gravitational pull on the earth. Since\[F = ma\] and \[F = G(M _{earth})(m _{you}) / R^2\]then the acceleration of the earth toward you is\[a = G(m _{you})/R^2\]
So if you weigh 50 kilograms, then the earth accelerates toward you at\[8.22(10^{-23}) m/s\]

Answer 8

What is r^2 here?

Answer 9

It's the distance between the masses, squared.

Answer 10

The distance between you and the center of the earth (presumably the radius of the earth, since you are standing on the earth).

Answer 11

(Or between their centre of masses.)

Answer 12

So, from my center of gravity to earths center of gravity? why squared?

Answer 13

Because through experimentation, it's been found that the magnitude of the gravitational forces follows this inverse-square law.

Answer 14

On a more basic level, because that is what Newton's law of gravitation says.

Answer 15

So if i weigh 50kg i would take 8.22 x 0.00000000000000000000001 / the distance between me and the center of the earth?

Answer 16

Quick note, the acceleration of the earth is negligible in comparison with your acceleration, but the pulls are exactly the same.

Answer 17

Jemurray! Were you the quantum physicist TT was talking about?

Answer 18

Good point, Jemurray! There's only one gravitational force between two objects.

Answer 19

How can that be true, if both of them have gravitational pulls? Are you saying the gravitational force is both of those added together?

Answer 20

Sorry for a confusing answer, Inopeki - the magnitudes of the pulls are exactly the same, but the direction is opposite.

Answer 21

Did you have a question about quantum mechanics, Inopeki?

Answer 22

He has many...

Answer 23

Oh! So a pen has the same magnitude of gravity towards the earth as the earth has towards the pen?

Answer 24

Jemurray, i dont even know where to start..

Answer 25

Start on a new thread ;-)

Answer 26

Good point.

Answer 27

Haha oh my... well it's a complicated subject, and very mathematically subtle, so I don't know how much I'd be able to relate. Start a new thread and I'll try to answer (some of) your questions.

Answer 28

By the way, in regards to the pen question - yes. A pen exerts the same force (pull) on the earth as the earth does on the pen, but in opposite directions. What actually happens as a result of that force (acceleration), however, depends on the size of the masses.

Answer 29

@Underhill thank you for the answer. I am aware of what you are explaining to me and I understand all that, but I'm very stubborn and childish in that kinda way of reasoning. I know that gravity works and I'm not trying to prove it doesn't, what I am trying to say is that even if I can use a theory and accept it as a good one i still don't know how it works. Why it does what it does?
So I still don't know how it works...

Also I am aware of how silly this sounds :D

Answer 30

@gogind. Completely reasonable.

Answer 31

Your point is perfectly reasonable, actually. We know through physics that gravity works; we don't how or why it works. But it's logical that everything has a cause, so we work to find a Higgs Field or Higgs Boson that can explain gravity. (Then we'll start trying to find the cause of THAT :-) )

Answer 32

How dont we know how it works after so many years?

Answer 33

There must be theories about it

Answer 34

There are several theories - physicists are working to validate one of them by finding, for example, a Higgs Boson.

Answer 35

What is a higgs boson?

Answer 36

(deleted long reply)...What Underhill said, that's pretty much it...

Answer 37

http://en.wikipedia.org/wiki/Higgs_boson

Answer 38

Thanks