Two Laws of Thermodynamics

Two Laws of Thermodynamics
Early researchers who first studied energy and its relationships and exchanges formulated two laws of thermo-dynamics.

The first law, also called the "law of conservation of energy," says that energy cannot be created or destroyed but can only be changed from one form to another. Think of the conversions that occur when coal is used to power a locomotive. First, the chemical energy of coal is converted
to heat energy and then heat energy is converted to ki- netic energy in a steam engine. Similarly, the potential
energy of coal or gas is converted to electrical energy by power plants. Do energy transformations occur in the human body? As an example, consider that the chemical energy in the food we eat is changed to the chemical energy of ATP, and then this form of potential energy is converted to the mechanical energy of muscle contraction.

The second law of thermodynamics says that energy cannot be changed from one form to another zvithout a loss of us-
able energy. Only about 25% of the chemical energy of gasoline is converted to the motion of a car; the rest is lost as heat. Heat, of course, is a form of energy, but heat
is the most random form of energy and quickly dissipates into the environment. Or as we have already mentioned, when muscles convert the chemical energy within
ATP to the mechanical energy of contraction, some of this energy becomes heat right away. With conversion
upon conversion, eventually all usable forms of energy become heat that is lost to the environment. And because heat dissipates, it can never be converted back to a form of potential energy.