Energy Flashcards
All the units used for energy
kilogram (kg), joule (J), metre (m), metre/second (m/s),
metre/second2 (m/s2), newton (N), second (s) and watt (W)
Energy Stores
energy stores: chemical, kinetic, gravitational, elastic, thermal, magnetic,
electrostatic, nuclear
Energu transfers
energy transfers: mechanically, electrically, by heating, by radiation
(light and sound)
What does the prinicple of energy state
In any process energy is never created or destroyed. (It is just transferred from one store to another.)
Equation for efficiency
(total energy output / useful energy output) x 100%
What is condution
Conduction is the transfer of thermal energy through a substance by the vibration of the atoms within the substance. Metals are good conductors because they have free electrons that can move easily through the metal, making the transfer of energy happen faster.
What is convection
Convection occurs in a liquid or gas. These expand when heated because the particles move faster and take up more volume – the particles remain the same size but become further apart. The hot liquid or gas is less dense, so it rises into colder areas. The denser, colder liquid or gas falls into the warm areas. In this way, convection currents are set up which transfer heat from place to place.
What is thermal radiation
Thermal radiation is the transfer of energy by infrared (IR) waves. These travel very quickly in straight lines.
Where is convection used?
Hot air balloon
What surface absorbs light the most, but reflects the least?
Dark surfaces
What surface absorbs light the least, but reflects the most?
Light (shiny) surfaces
How can we reduce insulation?
There are some simple ways to reduce this loss, including fitting carpets, curtains and draught excluders. Energy loss through windows can be reduced using double glazing. These kind of windows have air or a vacuum between the two panes of glass.
Equation for work done
Work done = force x distance moved
Law of work:
Whenever a force makes something move, work is done. The amount of work done is equal to the amount of energy transferred. Bonus: it is measured in Joules
Equation for gravitational potential energy (GPE)
mass x gravitational field strength (10 in Earth) x height
(m x g x h)
