P2: Heat Transfers Flashcards
What is Conduction?
When heat is transmitted through an object
What is convection?
When heat is transferred by movement of a heated fluid such as water or air
What is radiation?
When heat transfers through no contact or air movement but happens through a vacuum (space)
What is evaporation?
When water molecules are heated which make the particles bounce around and go faster so they become air
What are good conductors of electricity?
Copper, aluminium, gold, silver, graphite
What is insulation?
When heat cannot be transferred through objects
How would hot countries design their buildings?
Use materials that are good insulators so that the heat is trapped in the metal
How would cold countries design their buildings?
Use materials is low thermal conductivity so that the heat energy stays in the air
How to calculate energy transferred?
Mass,m(kg) x specific heat capacity,c (J/kg C) x temperature change ^0(c)
What is specific heat capacity?
The amount of energy needed to change the temperature of 1kg of the substance by 1 degree
State the consequences for energy transfer of a material with a high thermal conductivity?
The rate of energy transfer through the material is higher than for a material with a lower thermal conductivity
What key factors affect the rate of cooling of a building?
The thickness of the walls
The thermal conductivity of the walls
State three methods of reducing heat loss in a building?
Double glazing
Loft and wall insulation
Thicker walls
How cam the efficiency of a radiator be improved?
Installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the walls
How can the efficiency of boiling water in a pan be improved?
By placing a lid on the pan to reduce the heat loss from the top
