BesslerWheel.com

[Silvertiger]

Anyone who has ever taken physics knows that F=ma (force = mass x acceleration). The thing that always bugged me is that gravity is often referred to as a force, but the number given is an acceleration. Also, anyone who has ever taken a science class knows that science is a study based purely on observations, reproducing and/or measuring observations, and then explaining the nature of said observations, usually in the form of mathematical principles. Your weight is observed as a force because it is the product of your body mass and the acceleration due to gravity...but that's only the force that you exert upon the earth. It is also mutually understood that the earth acts upon you with an equal and opposite force, so that you don't keep falling toward the center.

But my question has always been, what is the FORCE of gravity? Well, here's where it seems different. We know that the earth has a mass, and we know that all of its mass accelerates upon itself, thus keeping it intact. And another thing, an overlooked scientific observation - acceleration has, is, and will always be a dependent variable. It is dependent on a net force acting. Has anyone EVER observed a spontaneous acceleration without a force already present to create it? Of course not. So why do we treat it like it does?

And finally here's where the math comes in. The mass of the earth is 5.9742E24 kg, and its inward acceleration due to gravity is 9.80665 m/s^2. With this information, it is easy to find the actual FORCE of gravity.

Using the formula F=ma, the force of gravity that is exerted upon the earth is 5.8587E25 N. Wow that's a really big number. O.O

And here's another question. What about Newton's Third Law? Math doesn't lie. There is an enormous amount of force acting upon the earth at all times, such that the earth must act back with an equal and opposite amount of force simply to maintain the net zero. So...Sir Newton would like to know that if the earth is pushing against something with this insane amount of force in all directions...then what is pushing back?

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Sure. Fine. Whatever.

[jim_mich]

Some think that the Earth is constantly growing. It grows a little from space dust and meteor impact. But is seems to be growing much faster than from capturing space debris.

If you take the force of Earth gravity and calculate the total energy, then use E=M×C^2 to convert the gravity energy into matter. and back calculate how long it would take for the conversion of gravity energy into matter, you will find that it roughly matches the current estimate of how old the Earth is.

In other words, matter blocks the cosmic force that we observe as gravity. This produces force, as there is more pressure from above than from below, because the Earth blocks some of the pressure from below. And that blocked energy turns into matter. And that matter accumulates and becomes planets. Which grow bigger over time. Some of the blocked energy heats the core of the planets causing them to become molten. Some planets grow so big that they become stars. The stars block so much gravity energy that they become very hot and radiate heat and light. Stars and large planets are often calculated to be less dense based upon orbit size and the amount of gravity attraction needed to maintain these orbits. But assume gravity has limits where larger diameter bodies block all of the gravity force and as the bodies grow bigger the gravity force is no longer related to mass but relates to body diameter. This makes the stars seem to be composed of much lighter materials.

Anyway, here is a link to much more reading on this subject by Stanley V. Byers ...

http://home.netcom.com/~sbyers11/index.html

[Fletcher]

That's because it's a gravity FIELD - a field of Potential borne of position.

F = m.a , so ANY force must have two parts to it.

1. a mass

2. an acceleration

If we put a hypothetical object we can see of NO mass into a gravity field, & its not acted on by anything else & free-to-move, we won't get a gravity force because we need a mass to manifest the 'g' force.

So, if we place that massless object in a complete vacuum of space [if there were such a thing] & within a gravity field it would not move - two objects can only have gravitational attraction if they both have mass.

What the gravity field does is provide effectively a constant acceleration [at near earth surface distances] regardless of the mass in the field - that's because any mass is made up of discreet atoms but they can be thought of as separate but bundled, each atom being accelerated by 'g' - this means that larger masses have more gravity force which we interpret as weight force whilst the 'g' acceleration remains the same for all masses.

This is counter-intuitive to what we normally observe with forces - we know that the larger the mass the more force must be applied to achieve the same acceleration - or put another way, the same force applied to two different masses will see the small mass accelerate faster.

That's because mass has inertia which is a resistance to change in state of motion - this doesn't apply to two different masses solely in a gravity field - they both accelerate at the same rate [all else being equal] - they still have inertia to overcome when moving in any other direction other than when aligned with the gravity field of influence - that's why it's a FIELD & not strictly a differential or gradient IMO.

I could be wrong but this is how I have rationalised it at the Newtonian level having had the same thoughts.

...................

What's pushing back is the four elemental forces of an atom trying to maintain equilibrium.

[Silvertiger]

That's very interesting. So would you say that the cumulative net of the other three fundamental forces acting throughout a mass are the very forces that are the cause of acceleration due to gravity? It would make sense, I suppose...having a huge mass, with three different types of interacting forces generating a net acceleration. It would definitely support the observed nature of acceleration being a dependent variable upon mass and force. The notion of gravity being a byproduct of those three fundamentals sounds very intriguing. Three non-contact forces defined by the existence and behavior of matter...so mass is still definitely involved...gets me thinking! :)

[Fletcher]

http://www.ric.edu/faculty/ptiskus/atomic_force/

I don't know - just what I was taught at school a long time ago & what I've learned since.

To answer your question that is why the hunt has been on for 50 years to find the higgs boson - the mass conferring quark of matter - this is an energy signature from the postulated higgs field which appears they have been found within 5 sigma's - that means to an accuracy of 0.9999 or 1 in a million chance of it not being the higgs boson & another quark.