thermal energy

• What is thermal energy?

  this refers to the energy moved from a hot object to a cold object.
• FILL IN THE BLANK : The _____ the temperature difference the ____ the rate of heat loss

  bigger and greater
• why can't we go below room temperature??

  the object is now at the same temperature , the room of the object are in thermal equilibrium.
• name the three methods by which heat moves

  - conduction

  -convection

  -radiation
• what is conduction

  the transfer of heat energy through a material without the movement of the material itself. Occurs mainly in solids
• explain why metals are good conductors?

  they have free electrons that are able to move along the material, colliding with the lattice ions causing them to vibrate so kinetic energy/internal energy increases
• give two examples of poor conductors of heat

  -plastic

  -wood

  -stone
• give two examples of good conductors of heat?

  copper and aluminium
• what physical state does conduction happen in?

  in solids
• what physical state does convection happen?

  fluids- liquids and gases
• what does the term convection mean

  the physical movement of the material due to the increase in temperature
• explain how convection works

  - the air gets hot

  -it expands

  -it becomes less dense

  -it rises

  -the cooler air flows to fill the atmosphere
• What are convection currents?

  the way that heat is transferred throughout a fluid
• what does radiation mean

  the transfer of heat energy through electromagnetic waves- does not require a medium, so it can occur in a vacuum
• FILL IN THE BLANKS- Black objects are the best ______ and _____ of heat

  absorbers and emitters
• what are aborbers

  they take in the heat
• what are emitters?

  they give out the heat
• what physical state does radiation happen?

  vacuum and gases
• how do reduce heat loss in conduction?

  by using a poor conductor
• how do reduce heat loss in convection?

  if it is a drink- put a lid on it to trap air/liquid by layers of clothing.

  in houses use fibre glass loft insulation that traps air.
• how do reduce heat loss in radiation?

  paint it sliver to reduce radiation as sliver is a poor emitter
• what is specific heat capacity

  the amount of energy required to raise the temperature of 1kg of a material by 1°C
• state the formula linking specific heat capacity , energy provided, mass and temperature

  E = mcΔT
• Calculate the energy needed to heat 2kg of water from 20°C to 100°C. The specific heat capacity of water is 4200J/kg°C

  672000J
• water of specific heat capacity 4200J/kg°C has 50kJ of heat added . If the mass of the water is 750g, what is the increase in temperature?

  16°C
• solid into liquid

  melting
• liquid into vapour/gas

  evaporating
• vapour/gas into liquid

  condensing
• liquid into solid

  freezing
• what is renewable resources

  easily replaced
• what are non-renewable resources

  not easily replaced once its gone it will take millions pf years to replace. - e.g. - fossil fuels and nuclear.
• What are the types of non-renewable resources?

  • Fossil Fuels
  • Coal
  • Oil
  • Gas
  • Nuclear
  • Uranium
• What are the types of renewable resources?

  • Wind
  • Wave
  • Solar
  • Geothermal
  • Biomass
  • Tidal
  • Hydroelectric power (HEP
• what material are in fossil fuels

  coal, gas and oil