We live in a world of motion. A main task of the engineer is to find
better and more efficient ways of transforming the energy locked in the
sun’s rays or in fuels, such as coal and the uranium nucleus, into
energy of motion. Almost all the world’s energy is now transformed by
rotating or reciprocating machines. We couple the energy of exploding
gasoline and air to our automobile’s wheels by a reciprocating engine.
The turbogenerator at a hydroelectric plant extracts energy from falling
water and turns it into electricity. Such rotating or reciprocating
machines are called _dynamic_ converters.