Physics Flashcards
Renewable / non renewable energy
Solar, wind, hydro, waves, tidal, biomass, geothermal
Oil, coal, gas, nuclear
Equations:
Work done
Power
GPE
Kinetic
Efficiency
Specific heat capacity
Force x distance
Power/energy
Force x change in heights
Mass x 0.5 x (speed) squared
Useful/total energy
Energy = mass x specific heat capacity x temp change
Convection (3)
• only occurs in fluids
• energy transferred to thermal store of liquid, particles jiggle and move apart, decreasing in density
• hot particles rise, cold particles fall, this creates a current
Conduction
• particles close together (that’s why only occurs for solids)
• metal has free electrons to move and carry energy
• heated particles vibrate more
Dissipation
Energy transferred to surrounding (mainly through thermal)
Thermal conductor vs insulator
Insulators can’t conduct thermal energy, whereas conductors can
Appliance: wasted vs useful energy
Light bulb
Electric heater
Electric toaster
Electric kettle
Hairdryer
Electrical motor
Light energy, thermal to surroundings
Thermal energy, light emitted
Thermal energy to toast, thermal energy to surroundings
Thermal energy to water, thermal energy to surrounding
Motor wind stuff, noise thermal energy
Kinetic energy, sound + thermal energy
Universal law of energy
Wasted energy
Useful energy
Friction
Energy can never be created or destroyed, only transferred
Energy transferred the way we want
Energy wasted
Contributes to wasted energy, lubrication can help reduce its effect
Hooke’s Law
Force is directly proportional to the extension of elastic object
Methods of energy transfer
Mechanical, electrical, heating, radiation
Energy stores
Kinetic
Chemical
Nuclear
Electrostatic
Elastic potential
Gravitational potential
Magnetic potential
Thermal
Infrared
All bodies emit and absorb infrared radiation
What is specific heat capacity?
How much energy needed to raise the temperature of 1kg of a substance by 1°c
Three ways to insulate a building
Cavity in the wall
Double glazed window
Thick bricks
Loft insulation
Aluminium foil
What does the material’s thermal conductivity tell you?
How well it conducts heat (thermal insulators don’t conduct well)
Three factors affecting thermal energy transfer
Mass
Thermal conductivity
Temperature difference
What is infrared
Type of electromagnetic radiation
How would a material remain at a constant temperature?
What is a black body?
Emit and absorb equal amounts of infrared
Absorbs 100% infrared, best emitter
Relationship between temperature and emission
High temperature = more infrared emission
Greenhouse gases that humans do
Deforestation, burning fossil fuels, livestock farming
Why do greenhouses gases increase the earth’s temperature
Earth absorbs and re-emits radiation from the sun, greenhouse gases absorbs and re-emits radiation back to earth
