Heating Cooling .
Transfer of HEAT can happen in 3 ways:
Conduction, Convection, Radiation
Heat can travel through Heat is transferred by the heat travels as
solids. E.g. a metal spoon movement of liquids or electromagnetic waves
in hot soup heats up gases called “Infrared waves”
Like Boiling water, or The hotter the object the
Hear, Heat energy flows Heater in a room ore radiation it emits.
quickly . There are no particles
heat travels as involved !
Best conductor of Heat: METALS Hot particles travel upwards While color absorbs more
radiation
Poor conductors: Air, fur, glass..
Example, sun heat
reaching
the earth
What is Heat. What the heat unit
Heat is a transfer of Energy from higher temperature object to lower
temperature object. Units are called Joules J, or Kilojoules K
What is temperature. How to measure it
It is a measurement of how hot or cold something is. We measure it with a
Thermometer in Degrees Celsius (oC)
What is absolute Zero
Temperature at which particles stop moving and have no heat energy.
This temperature is -272 oC
Kevin Scale: It is a scale used for scientific work and starts at absolute Zero.
Names of change of state form:
- Evaporation = Liquid to Gas
- Condensing = Gas to Liquid
- Melting = Solid to Liquid
- Freezing = Liquid to Solid
Which materials are best heat conductors
Metals, as heat travels through them easily
What is an Insulator. Name 3
A Poor conductor of Heat: Air, Fur, Feather, Wool, plastic foam, glass, mineral
wool.
Why Liquids and Gases can carry heat?
Despite being poor conductors, they can carry heat because their particles
move around freely
Why convection cannot happen in Solids?
Because the particles are held in a framework and cannot move around like in
liquids or gases.
Why a vacuum Flask can keep drinks cold or hot few hours
- It has a stopper that reduces any heat loss caused by to convection and
conduction
- Heat loss is also saved by the space between the walls as it vacuums the
air.
- Also, the silver lining of the walls reduces heat loss by radiation.
(DIAGRAM in COPY)
