00:01
In this question, we've been asked to find the maximum kinetic energy of a beta minus a particle that is emitted when cobalt 60 decays under beta minus decay.
00:17
So this is what we begin with, cobalt 60, which has 27 protons.
00:24
So to answer this question, what i'm going to do is first write down the decay equation.
00:28
And from the decay equation, we can then use the masses prior to the decay and after the decay.
00:36
And if we take these away from each other, this mass difference can be converted into an energy using e equals mc squared.
00:43
And this energy is equal to the maximum kinetic energy of the emitted beta particle.
00:52
In beta minus decay, we have a neutron converting into a proton.
00:59
So our number of protons is going to increase to 28, but our number of nucleons remains the same.
01:05
And the atom with 28 protons is nickel.
01:09
So this is nickel.
01:11
We then have our beta minus particle and a neutrino.
01:17
Now the maximum kinetic energy of our beta minus particle is going to occur when we actually have no neutrino emitted.
01:26
So i'm just going to rub this away.
01:27
And now what we are going to do is we're going to take the mass of the cobalt 60, so m -cobalt, and from that we're going to take away the mass of the nickel and the mass of the beta particle, and then convert this into an energy by timesing by c squared...