Energy: The capacity to cause change.

Kinetic Energy: Energy can be associated with the relative movement of objects; this energy is called kinetic energy.

Heat/Thermal Energy: Kinetic energy associated with the random movement of atoms or molecules.

Potential Energy: An object not presently moving may still possess energy.  Energy that is not kinetic is called potential energy.  It is an energy that matter possesses because of its location of structure.  Ex. Water behind a damn. The study of the energy transformations that occur in a collection of matter is called thermodynamics.

Closed System: Such as that approximated by liquid in a thermos bottle, is isolated from its surroundings.

Open System: Energy (and often matter) can be transferred between the system and its surroundings.  Organisms are open systems because they absorb energy and release heat and metabolic waste products, such as carbon dioxide, to the surroundings.

First Law of Thermodynamics: The energy of the universe is constant.  Energy can be transferred and transformed, but it cannot be created or destroyed. This is also called the principle of conservation of energy.

For example, the chemical (potential) energy in food will be converted to the kinetic energy of a cheetah.

Second Law of Thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe.  For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism.

Entropy: a measure of disorder, or randomness.  A logical consequence of the loss of unstable energy during energy transfer or transformation is that each such event makes the universe more disordered.  The more randomly arranged a collection of matter is, the greater its entropy.

·For a process to occur on its own, without outside help (an input of energy), it must increase the entropy of the universe.  Let’s first agree to use the word spontaneous for a process that can occur without and input of energy.  Note that as we’re using it here, the word spontaneous does not imply that such a process that can occur quickly.  Some spontaneous processes may be virtually instantaneous, such as an explosion, while others may be much slower, such as the rusting old car over time.  A process that cannot occur on its own is said to be nonspontaneous; it will happen only is energy is added to the system.  Water flows downhill spontaneously, but moves uphill only with an input of energy, for instance when a machine pumps the water against gravity.  For a process to occur spontaneously, it must increase the entropy of the universe.