Practical steam engines utilize 450ºc steam, which is later exhausted at 270ºc.
(a) what is the maximum efficiency that such a heat engine can have?
(b) since 270ºc steam is still quite hot, a second steam engine is sometimes operated using the exhaust of the first.
(c) what is the maximum efficiency of the second engine if its exhaust has a temperature of 150ºc?

(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

the moon affects the earth gravitation ally, causing certain motions of that body and also producing tides in its ocean and atmosphere. the tidal wave in our atmosphere is, however, far too minute to be an effective cause in any known meteorological phenomenon.

explanation: