Owen Duffy wrote in
:

....
When the switch is closed, current flows into the line. Until t=2T
seconds, the current If that flows into the line equals 100V/(100+100
ohms) = 0.5A, during which time the resistor dissipates heat at the
rate of I^2*R = 100W. The voltage of the wave Vf travelling from the
source is I*Zo = 50V. This situation is constant until t=2T seconds.
....

David Ryeburn is awake, even if I wasn't at 5.38 when I wrote this.

should be ...during which time the resistor dissipates heat at the
rate of I^2*R = 25W...

It doesn't materially change anything, but I messed up!

Owen