Maslow's Hierarchy of Needs. Definition. Maslow's hierarchy of needs is a theory of motivation and personality developed by the psychologist Abraham H. Maslow (1908â1970). Maslow's hierarchy explains human behavior in terms of basic requirements for survival and growth.
When you use ice to cool the ingredients for ice cream, the energy is absorbed from the ingredients and from the outside environment (like your hands, if you are holding the baggie of ice!).
1 Similarly, the amount of energy absorbed when a substance melts, and released when the same amount of substance freezes, is the same.  Sublimation, a substance going straight from solid to gas phase, also involves the absorbing of energy.