Mechanics deals with the response of bodies to the action of forces in general, and dynamics is a branch of mechanics that studies bodies in motion. The principles of dynamics can be used, for example, to solve practical problems in aerospace, mechanical, and automotive engineering. These principles are basic to the analysis and design of land, sea, and air transportation vehicles and machinery of all types (pumps, compressors, and reciprocating and gas-turbine internal combustion engines). A review of some principles relevant to heat engines is presented here.