If a locomotive uses steam at 100°C, and dumps heat into air
at 220°C. what is the highest
possible efficiency it could have?

79%

Explanation:

The following data were obtained from the question:

Input temperature = 100°C

Output temperature = 22°C

Efficiency =.?

Next, we shall convert the temperature from celsius to Kelvin temperature. This is illustrated below:

T (K) = T (°C) + 273

Input temperature = 100°C

Input temperature = 100°C + 273 = 373K

Output temperature = 22°C

Output temperature = 22°C + 273 = 295K

The efficiency of the locomotive can be obtained as follow:

Input temperature = 373K

Output temperature = 295K

Efficiency =.?

Efficiency = output /input x 100

Efficiency = 295/373 x 100

Efficiency = 79%

Therefore, the efficiency of the locomotive is 79%.