EFFICIENCY

===Efficiency=== Energy loss in devices (like motors) is caused by forces such as friction where parts slip over each other or by drag which opposed the motion of an object through a fluid. The energy loss is usually called heat energy transferred to other sources. For a moving object in a fluid, some of the energy used to move the object is going into moving the fluid (e.g. air) as the object passes through it.Metal parts slipping over each other cause the internal energy of the metal (i.e. the movement of the metal atoms) to increase, increasing the metal's temperature. [image:http://www.bbc.co.uk/staticarchive/9e302ad86680cff0a2e9c42f8a7eaa996419b22b.gif] Source: BBC ===Calculating Efficiency=== Efficiency is measured as a percentage. E.g. A car engine is 25% efficient. This is a way of saying that of the Chemical Potential Energy stored in the petrol, only 25% of it actually goes into moving the car as Kinetic Energy. 75% is lost as other forms such as Heat Transfer to the connected engine parts or as Sound which is kinetic energy lost to the air. Efficiency is calculated by: [image:https://i.imgur.com/zMly9LW.png] Source: one-school.net