Energy dissipation

• Dissipation is a term that is often used to describe ways in which energy is wasted.
• Any energy that is not transferred to useful energy stores is said to be wasted because it is lost to the surroundings. 
• In a mechanical system, energy is dissipated when two surfaces rub together. Work is done against friction which causes heating of the two surfaces - so the internal (thermal) energy of the surfaces increases. Adding lubricant between the surfaces reduces this friction and so less heat is wasted.
• Energy is usually lost by heating up the surroundings though sometimes energy is dissipated as sound waves.