Topic 1 Conservation and Dissipation of Energy Flashcards
What is dissipation?
Energy becoming spread out to the stores of surrounding objects (usually wasted thermal energy)
What is lubrication?
A method of reducing unwanted energy transfers by application of lubricant (e.g. oil) to reduce friction. Occurs in machines
What is insulation?
A method of reducing energy transfers by the use of insulators. Occurs in buildings e.g. loft insulation
What is conservation of energy?
The law that states that energy cannot be created or destroyed
What is a closed system?
An isolated system in which no energy transfers take place out of or into the energy stores of the system
What is work?
Work is done on an object when a force makes the object move
What is a system?
Object or group of objects
What is friction?
A contact force resisting the relative motion between two surfaces. Friction in machines always causes energy to be wasted
What is input energy?
Energy supplied to a device
What is useful energy?
Energy transferred to where it is wanted in the way it is needed
What is wasted energy?
Energy that is not usefully transferred
What is the efficiency of a device?
The proportion of the total input energy that is transferred in useful ways
What does mechanical mean?
Energy transferred by forces acting on objects
What does electrical mean?
Energy transferred when an electric current flows through a device
What is radiation?
Energy transferred by electromagnetic radiation (light, microwaves, sound etc.)
What does heating mean?
Energy transferred by conduction, convection or radiation
What is a chemical energy store
An energy store that can be changed by bonds being made/broken
What is kinetic energy?
An energy store that all moving objects have
What is gravitational potential energy
Energy stored in objects raised up against the force of gravity (possessed by anything that can fall)
What is thermal (heat) energy?
Energy that flows from hot objects to colder objects
What is a nuclear store?
Energy stored in the nuclei of atoms. Can be released by the fusing or splitting of nuclei
What does magnetic mean?
Two separated magnets that are attracting or repelling
What does vibrational mean?
Energy from vibrations or moving to and fro (e.g. a pendulum)
