00:01
For this problem on the topic of quarks, we want to answer various questions about beams of protons that are emerging from a particle accelerator and colliding with nuclei in a copper target.
00:12
Now, firstly, we use the relativistic relationship between speed and momentum for part a, and we get the momentum p is equal to gamma mv, which is mv divided by the square root of 1 minus.
00:31
V over c squared.
00:35
We can now solve for the speed v, and we get v over c equal to the square root of 1 minus 1 over pc over mc squared, all squared plus 1.
00:57
Now for an antiproton, mc squared is 938 .3 mega electron volts, and pc is 1 .1919.
01:06
Electron volts or 1 ,190 mega electron volts.
01:10
So the speed v is equal to 1 minus 1 over all of this multiplied by c, 1 ,1190 mega electron volts divided by 938 .3 mega electron volts, and all of this squared plus 1.
01:42
This gives the speed of the antiproton to be 0 .785 times c.
01:56
For part b and for the negative pion we have mc squared equal to 193 .6 mega electron volts and pc is the same as before.
02:06
So v is equal to c times the square root of 1 minus 1 over 1.
02:16
1 .1.
02:16
1 .1.
02:16
1.
02:16
1.
02:16
1...