the equation F=Gxy/(d^2) relates the force of gravity to the mass of the two bodies and the distance between them where F is the pull of gravity on the two bodies, G is the gravitational constant (6.67300 × 10^-11 m^3 kg^-1 s^-2), x is the mass of one body, y is the mass of the other body, and d is the distance between the centers of them. Usually x and y are written as m with different subscripts to differentiate between the two. another equation is F=mg where F is the gravitational force exerted on the object (or weight), m is the mass of the object, and g is the acceleration of gravity. g is 9.8 m/s^2 on the surface of the Earth. Not sure if that's what your looking for. In simpler terms, any body with mass is affected by gravity and effects other bodies with mass. Also, gravity bends space-time, so gravity doesn't affect just particles with a non-zero light. ex. light cannot escape the enormous gravitational pull of a black hole.

gravity
the force that attracts a body toward the center of the earth, or toward any other physical body having mass. For most purposes Newton's laws of gravity apply, with minor modifications to take the general theory of relativity into account.
• the degree of intensity of this, measured by acceleration.

mass
the quantity of matter that a body contains, as measured by its acceleration under a given force or by the force exerted on it by a gravitational field.
• (in general use) weight.

ever heard of google? or dictionary.com?

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