This is also known as thelaw of conservation of energy. The first law of thermodynamics is the application of the conservation of energy principle to heat and thermodynamic processes. The first law makes use of the key concepts of internal energy, heat, and system work. It is used extensively in the discussion of heat engines.
Definition of associate. 1 : closely connected (as in function or office) with another : sharing in responsibility or authority associate judges. 2 : having secondary or subordinate status associate membership in a society.
association. 1  an organization of people with a common purpose and having a formal structure. 2  the act of associating or state of being associated. 3  friendship; companionship: Their close association did not last long. 4  connection or combination.