|Week of||Jan 14||Feb 4||Mar 4||Apr 1||Phy 360 page|
|Jan 21||Feb 11||Mar 18||Apr 15|
|Jan 28||Feb 18||Mar 25||Apr 22|
28 Jan Derive length contraction, as I hadn't done that before.
Show qualitatively how magnetic forces arise from electrical forces plus an understanding of simultaneity.
State without derivation the basic equations for energy and momentum
Explore some special cases, starting with the non-relativistic limit where v << c. In this case the momentum is small, so the p2c2 term is much smaller than the other, leading to the statement the the energy E is approximately mc2. Put this into the first equation and you find that the momentum is approximately mv.
The kinetic energy requires a bit more work to extract. You can eliminate p between the two equations, and get
If v is not equal to c, then this is
For small speeds, use the binomial expansion to get
The kinetic energy is the difference between the total energy and the energy when at rest.
The other case, where v = c, implies that m = 0. Return to the original pair of equations and you have
This is the energy-momentum relation for photons. Light carries momentum as well as energy even though it has zero mass.
30 Jan Applications of the mass-energy relations. Define the unit of energy the electron-Volt.
1 Feb Do one of the homework problems in some detail -- one involving the twin effect.
Set up the problem of solving for the proper acceleration, doing it the brute-force way, but not finishing it.