P1.1 Heating processes Flashcards
Give examples of each energy Chemical energy Nuclear energy Thermal energy Elastic potential energy Electrical energy Light energy Gravitational potential energy Sound energy Kinetic energy
Battery Nuclear power station Hot water Wind up toy Plug Light bulb Something falling Siren Spring
What do all objects do?
emit and absorb infrared radiation
What happens if the object is hotter than its surroundings?
It will emit more radiation than it absorbs
What happens if the object is cooler than its surroundings?
It will absorb more radiation than it emits
What is a good absorber and emitter of infrared radiation?
Give an example
Dark matt surfaces
solar panels
What is a poor absorber and emitter of infrared radiation?
Give an example
Light shiny surfaces
thermos flask
What is a good reflector and what is it used for?
Light shiny surfaces
Used to keep heat in or minimise heat radiation to keep things cool
Give facts about gases (3)
- Far apart
- Random arrangement
- Moves quickly in all directions
Give facts about liquids (3)
- Close together
- Random arrangement
- Move around each other
Give facts about solids (3)
- Close together
- Regular pattern
- Vibrate on the spot
What happens when you heat a solid? e.g. ice
The kinetic energy increases which weakens the interparticle bonds allowing it to melt
Name 3 transfers of energy
- Conduction
- Convection
- Evaporation
Describe convection
1) heat warms up the liquid or gas
2) The particles become less dense so they rise
3) The further away from the heat source the cooler they get
4) They become more dens and sink
Describe conduction
Particles passing through an object due to the amount of energy they have
What is good about a vacuum flask? (3)
- A vacuum between two walls to stop conduction and convection and heat loss (conduction can’t happen without particles)
- Silvered walls to stop heat transfer by infrared heat radiation
- Top is made an air-filled plastic cap to stop conduction and heat loss
What does a U-value do?
Measures how effective a material is in an insulator
Amount of air particles that move through 1m squared space
What does a U-value mean?
- High U-value = good conductors of heat (poor insulators)
- Low U-value = good insulators (poorer conductors)
How do you work out the specific heat capacity?
E = m x c x θ
What do these symbols mean? E m c θ
Energy transferred in joules
Mass of material in kilograms
Specific heat capacity J/kg (degrees)C
Temperature change in Celsius
What can high heat capacity materials do?
They can store lots of energy when heated and can release a lot of energy if cooled down
