physics (energy (energy stores and systems (when a system changes energy…
most energy transfers involve some waste energy
useful devices are only useful because they can transfer energy from one store to another.
as youll probably have gathered by now some of the input energy is usually wasted by being transferred to a useless energy store- usually a thermal energy store
how to work out efficiency
energy resources and their uses
reducing unwanted energy transfers
wind solar and geothermal
conservation of energy and power
hydro electricity, waves and tides
specific heat capacity
biofuels and non-renewables
kinetic and potential energy stores
trends in energy resource use
energy stores and systems
the enrgy stores are: thermal energy stores, kinetic energy stores, gravitational potential energy stores, elastic potential energy stores chemical, magnetic electrostatic and nuclear energy stores
when a system changes energy is transfered
a system is just a fancy word for a single object or a group of objects that your interested in.
when a system changes, energy is transferred. it can be transferred into or away from the system, between different objects in the system or between different types of energy stores
closed systems are systems where neither matter nor energy can enter or leave. the net change in the total energy of a closed system is always zero
energy can be transferred by heating
take the example of boiling water in a kettle-you can think of the water as the system. energy is transferred to the water by heating, into the waters thermal energy store.
you could also think of the kettles heating element and the water together as a two object system. energy is transferred electrically to the thermal energy store of the kettles heating element which transfers energy by heating to the waters thermal energy store
work done is just another way of saying energy transferred- they're the same thing
work done can be when current flows or by a force moving an object.
scales and vectors