Y9 physics Flashcards
What are the 8 energy stores
chemical, kinetic, magnetic, electrostatic, elastic, gravitational, thermal, nuclear
What are the 4 energy transfers
mechanically, electrically, heating, radiation
Principle of conservation of energy
Energy cannot be destroyed or created, only transferred
Efficiency equation
Efficiency = useful energy output/ total energy output x 100
3 thermal energy transfers
Conduction
Convention
Radiation
What is conduction
Main energy transfer in solids
- Transfer of thermal energy through a substance by the vibration of the atoms within the substance
What is convention
Main energy transfer in gases and liquids
- expand when heated because the particles move faster and take up more volume, particles remain the same size but become further apart
What is radiation
Transfer of energy by infrared waves
- hotter the object, more infrared radiation can be radiated in a given time
- travel very quickly in straight lines.
Why are metals good conducters
have free electrons that can move easily through the metal, making the transfer of energy happen faster.
Light shiny surfaces relation to emission absorption and temp
Good reflectors of radiation and poor at absorbing
Dark surfaces relation to emission, absorption and temp
Poor reflectors good at absorbing
good at emitting
Ways of reducing unwanted energy transfer, such as insulation
good insulating material = poor conductor that contains trapped air
Poor conductor (non-metal) prevents heat transfer
Work done equation
work done (J) = Force (N) x distance moved (m)
Gravitational potential energy equation
Gravitational potential energy (J) = Mass (kg) x gravitational field strength (N/kg) x height (m)
Kinetic energy equation
Kinetic energy (J) = 0.5 x mass (kg) x velocity (m/s) 2
