Physics fags, why is this true? The part after the first full stop.

Inverse square law.

>>9098325
>why is the inverse square law true
Do a derivation m8.
It also applies to the flux from a radioactive source, but that's because of the solid angle.

>>9098333
I didn't know there was something called the inverse square law.

>>9098331
So in complete brainlet terms, it will be 1/4 of the force of a star that is half the distance because you'll divide by a distance that is twice as large (and also squared)?

>>9098325
because of experimental data

>>9098369
F = -GMm/r^2

it's giving an example of the 1/r^2 law.

star at .5r
1/(.5r)^2 = 1/(.25r^2) = 4/r^2

star at r:
1/r^2.

star half as close = 4x stronger gravity force. They are wording it kind of weird in the passage.

Intuitively, the inverse square law is true for forces like gravity and em because the loci of points a certain distance away from a point is a sphere. The surface area of a sphere increases by r squared, so the amount of force spread over that area decreases by r squared.