00:01
In this exercise, we have a neutron pion represented by pi 0 that has an average lifetime delta t of 8 .4 times 10 to the minus 17 seconds, and a mass that is 264 times the mass of the electron.
00:24
And in the first part of the question, we have to find what is the uncertainty in the mass of the pion.
00:34
Given the rest energy relation that the energy is equal to mc square.
00:44
Well, first, let's use the heisenberg's uncertainty principle, the energy momentum, i'm sorry, the energy time uncertainty principle, that states that delta t times delta e, where delta t is the uncertainty in the time and delta e in the energy is greater or equal than, h bar over 2.
01:11
Now use that delta e is equal to delta m times c squared.
01:19
So we have the delta t times delta m times c squared is greater or equal than h bar over 2.
01:28
So delta m is greater or equal than h bar over 2 delta t c squared.
01:36
So this is h divided by 4 pi, delta t c squared and if we substitute the numbers we have that h is 6 .63 times 10 to the minus 34 joules second divided by 4 pi times delta t that the t is 8 .4 times 10 to the minus 17 seconds times c squared c is 3 times 10 to the 8 minutes per second so that's a m is greater or equal than 6 .98 times 10 to the minus 36 kilograms...