What is Newton’s law of gravity?

Actually called Newton’s law of gravitation, it describes the degree to which one body of matter attracts another.

That attraction is in direct proportion to the product of the bodies’ masses, and in inverse proportion to the square of the distance between them.

This law can be expressed in a formula first set forth in 1687:

F = G (mi m2)

F is the attractive force; G is the gravitational constant, 6.67 x 10-8 dyne•cm2/gm2; m1 and m2 are the two masses; R2 is the distance squared.

Generations of schoolchildren have ignored the formula and remembered, “Whatever goes up must come down.”