1) The masses of the neutrinos are still not precisely determined, but let us as
ID: 2124271 • Letter: 1
Question
1) The masses of the neutrinos are still not precisely determined, but let us assume for the purpose of this problem that the mass of an electron neutrino is one millionth the mass of an electron.
What is the kinetic energy, in eV, of an electron neutrino moving at 0.954c?
2) You are assisting in an anthropology lab over the summer by carrying out 14C dating. A graduate student found a bone he believes to be 2.40 x 10^4 years old. You extract the carbon from the bone and prepare an equal-mass sample of carbon from modern organic material. To determine the activity of a sample with the accuracy your supervisor demands, you need to measue the time it takes for 1.50 x 10^4 decayse to occur.
What activity of the modern sample is 1.10 Bq. How long does that measurement take? answer in s
It turns ou that the graduate student's estimate of the bone's age was accurate. How long does it take to measure the activity of the ancient carbon? answer in s
Explanation / Answer
1)
E = E0 / (1 - (v/c)^2)^1/2 = E0 / (1 - .910)^1/2 = 3.333 E0
Where E is the total energy and E0 the rest energy
So Ek = E - E0 = 2.333 E0 the kinetic energy
The rest energy of the electron is .511MeV
The rest energy of the neutrino = .511 eV (1 millionth of the electron)
So Ek = 2.333 * .511 = 1.1923 eV the kinetic energy of the neutrino
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