00:01
Number 10.
00:03
There's a star that has twice the mass of the sun.
00:06
So here's the mass of the sun, so we have twice that.
00:10
Collapses and becomes a neutron star.
00:14
And we want to know what is the radius of it.
00:16
We're supposed to treat it like an atom.
00:19
So the equation for the radius of an atom is this r0, which is a, that's just a constant.
00:28
So that's 1 .2 times 10 negative 15th.
00:35
And a, that's the mass number.
00:38
But when a star becomes a neutron star, the protons and electron combined to make neutrons.
00:43
So this is the mass of one neutron.
00:47
So mass is conserved...