4.1-4.17 Flashcards
Energy stores and transfers
Energy is either stored in a certain way or is being transfered. It can not be anything other than than stored or transfered
Chemical (energy stores)
The energy stored associated with chemicals bond, such as those between molecules(food, muscles, electrical cells)
kinetic (energy stores)
The energy associated with a moving object (Runners, busses, comets)
Gravitational (energy stores)
The energy associated with an object at a height (aeroplanes, kites, mugs on a table)
Elastic (energy stores)
The energy stored when an object is streched, squashed or twisted (Drawn catapullts, compresed springs, inflated balloons)
Thermal (energy stores)
In most cases this is the vibrations of the particles in the object. In the hotter objects, the particles vibrates faster (The human bodies, hoy coffees, kettle
Magnetic (energy stores)
The energy stored when like poles are pushed closer together or when unlike poles are pulled further apart (fridge magnets, compasses and magnet trains which use levitation)
Electrostatic (energy stores)
The energy stored when like charges are moved closer together or when unlike charges are pulled further appart (Thunderclouds, Von de Graaff
Nuclear (energy stores)
The energy associated with nuclear interactions (Nuclear fusion of hydrogen and helium in the sun, Uranium - 245 undergoing fission)
mechanically (energy transfers)
A force moving an object through through a distance
Electrically (energy transfers)
Charges moving due to a potential difference
by heating (energy transfers)
Due to temperature difference
by radiation (energy transfers)
energy tranferred as a wave e.g. light, sound and infrared radiation
Conservation of energy
Energy can not be destroyed or created, so it is always stored or transfered. This means that energy is regularly transfered from one store to another, although sometimes it is considered to be ‘wasted’ when it is transferred to a store that is not useful
The efficiency of an energy conversion system is defined as:
efficiency = useful energy output/ total energy output x 100%
