The First Law of Thermodynamics is read "Delta U = Q - W." Explain what each of these terms means. Be sure to explain the minus sign.

Estimate the work done in compressing one cubic meter of air by 5% (start at room temperature and pressure).

Explain how it is possible to compress a sample of gas to half its original volume without changing its pressure.

Estimate the coefficient of performance of a typical househould refrigerator.