2. As a mass moves away from a larger mass
with a radial gravitational field, the force
felt is proportional to one over the radius
squared.
So, if the initial radius is r and the force felt
is F, when the radius increases to
2r, because the equation is 1/r^2 the force
becomes F/4.
The same applies for the intensity of
radiation from a source.
4. Intensity – I – is the energy that flows
through a certain area in a second. It is
measured in Watts per metre. W/m^2.
The gamma rays from a point source
spread out to cover a sphere shape.
The further the distance, the same
energy is spread out over a bigger
area, so the intensity decreases.