A refrigerator takes in 20 J of work and exhausts 50 J of heat. What is the refrigerator's coefficient of performance?

A certain gas occupies a volume of 4.3 L at a pressure of 1.2 atm and a temperature of 310 K. It is compressed adiabatically to a volume of 0.76 L. Determine the final pressure, assuming the gas to be an ideal gas for which $\gamma = 1.4$.

The normal airflow over the Rocky Mountains is west to east. The air loses much of its moisture content and is chilled as it climbs the western side of the mountains. When it descends on the eastern side, the increase in pressure toward lower altitudes causes the temperature to increase. The flow, then called a chinook wind, can rapidly raise the air temperature at the base of the mountains. Assume that the air pressure p depends on altitude y according to

$$p = p_0 exp (-ay)$$

, where

$$p_0 = 1.00 atm$$

and

$$a = 1.16 × 10^-4 m^-1$$

. Also assume that the ratio of the molar specific heats is γ = 4/3. A parcel of air with an initial temperature of -5.00°C descends adiabatically from

$$y_1 = 4267 m$$

to y = 1567 m. What is its temperature at the end of the descent?