What is gravity and how does it attract objects?

[nathankco]

I want to know what's gravity. <:D
How's it attract objects?
Anything that are massive and dense consist gravity?

 

[DaveC426913]

We don't really know.

Current theory models gravity as a curvature of spacetime. Objects follow null geodesics (fancy phrase for 'straight lines') through this curved space so that, to our eyes, they appear to curve (like how a baseball curves back toward the ground).

It is the presence of mass that curves space, so anywhere there is mass (even the smallest atom), there will be some curvature of spacetime.

Mass tells spacetime how to curve; spacetime tells mass how to move.


There are a gazillion PF threads on the this topic for the reading.

 

[brno17]

I want to know what's gravity. <:D
How's it attract objects?
Anything that are massive and dense consist gravity?

Gravity is a pull from the Earth's mass.

Everything has gravity EVEN YOU. We try to attract things by our Gravitational field.

The more your mass the stronger gravational field.

Hence the reason why the moons gravity is less than the Earth's.

The equation to this is GM*m / r

GM is a gravitational constant m is the mass r is radius from center.

So for ex if you want to find your gravitational strength you muliply the constant (I forgot it) by you mass in Kg devided by how far the object is from you in m.

 

[DaveC426913]

Gravity is a pull from the Earth's mass.

Or anything else.

The equation to this is GM*m / r

F = G . m/r^2

(And you only need M and m if you are figuring total force between two objects)

 

[nathankco]

Thankyou guys! Thankyou!

 

[Doc Al]

F = G . m/r^2

You left out M.

(And you only need M and m if you are figuring total force between two objects)

What do you mean by 'total force'? As opposed to what?

 

[K^2]

Gravity can mean force of gravity or acceleration due to gravity. I think that's what Dave is getting at. Though, usually the little m is the one reserved for test mass, and big M is used for body generating the pull.

Naturally, if two masses are comparable, you cannot use this formula directly.