(a) 0.249 (24.9 %)
The maximum efficiency of a heat engine is given by

where
Tc is the low-temperature reservoir
Th is the high-temperature reservoir
For the engine in this problem,


Therefore the maximum efficiency is

(b-c) 0.221 (22.1 %)
The second steam engine operates using the exhaust of the first. So we have:
is the high-temperature reservoir
is the low-temperature reservoir
If we apply again the formula of the efficiency

The maximum efficiency of the second engine is

Answer:
.737 v
Explanation:
Since they are in series....they all have the same current running through them.....find the total resistance to calculate the current:
R = 67 + 83 + 433 + 309 = 892 ohm
V/R = current = 7.92 / 892 = 8.87 mAmps
Now the voltage across ecah resistor is I R
for the second one 8.87 ma * 83 ohm = V = .737 V
A standing wave is the result of a reflection.