Modern Physics Homework
Homework
4: Due
Friday, October 9.
We will have an Exam on relativity and Waves
on Monday, October 19.
1. A spacecraft is heading out
of the solar system with a velocity v, directly away from the earth. They transmit data back at a frequency of 1
MHz. If we receive the data at a
frequency of 0.9 MHz, how fast are they traveling? (cf. problem 51.)
2. A neutron is moving with a
speed of 0.9c. What is its energy (in MeV) and Momentum (in MeV/c)?
3. A particle has an energy of 1MeV and a momentum of 0.99 MeV/c. (cf. problem 59.)
a) What is its speed in units
of c?
b) What is its mass in MeV/c2?
4. Someone tells you that a
particle has an energy of 10MeV and a momentum of
11MeV/c. What do you think of this? Explain!
5. A free neutron is an
unstable particle and will decay to a proton and electron, and anti neutrino
which can be approximated as having 0 mass.
How much energy will this decay release?
6. Find the binding energy of 7Li
in MeV. (The
mass of 7Li = 7.016004 u)
7. A Carbon-14 nucleus decays
to a 14N nucleus plus an electron (and an antineutrino again). How much energy (in MeV)
is released in this reaction?
The
table below lists the masses of some particles in atomic mass units, amu. (You can check Wikipedia for more information about atomic mass
units.) Appendix 8 in the back of the
book has the masses of many atoms in amu. 1u = 1.66×10-27kg.
|
Oblect |
Mass (u) |
MeV/c2 |
|
|
1.00 |
931.5 |
|
Electron |
0.00054858 |
0.5110 |
|
Proton |
1.007276 |
938.27 |
|
Neutron |
1.008665 |
939.57 |
|
H |
1.007825 |
938.78 |