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!).
Ice must absorb energy in order to melt (melting is an endothermic process *), so heat is transferred from the environment (which includes your ice cream mixture!) to the ice, making the ice cream mixture colder. You can control how fast the ice cream forms, by modifying the amount of salt you use.