Heat Energy Flashcards
Conduction
The transfer of energy from particle to particle, from the hotter end of the object to the cooler end of the object.
Convection
The transfer of energy as particles move from place to place, from hotter part of liquid or gas to the colder part.
Infrared radiation
As the particles vibrate they emit an invisible type of light called infrared radiation, as they do this they loose energy and move less so the temperature of the object falls.
What happens the faster the particles vibrate in IR?
The more the particles vibrate the more IR they emit, so the hottest object emits the most IR.
What happens when particles absorb IR?
It causes them to gain energy and move more so the temperature of the object rises.
Hot objects
Emit more IR than they absorb, so overall they cool down.
Cold objects
Absorb more IR than they emit, so overall they warm up.
Dull, dark coloured surfaces
Good emitters and absorbers of IR.
Shiny, light coloured surfaces
Poor emitters and absorbs of IR, they reflect it way instead, away from the object on the outside and back into the object on the inside.
How does IR travel?
It does not require any particles in order to travel between particles and so can transfer heat energy through solids, liquids, gases and a vacuum of empty space.
Expansion
The particles move further apart from each other, this causes the object overall to get bigger. Consequently the density is also reduced.
What does heat energy do to the particles?
Heat energy cause the particles to move faster which, in turn, causes changes of state.
What happens when 2 objects of different temperatures are placed in contact with each ther?
When 2 objects of different temperatures are placed in contact the hotter object will cool down and the colder one will heat up until they are both the same temperature.
What happens to the kinetic energy in a particle when the objects gets hotter and colder?
When the hotter object gets colder it looses kinetic energy and when the colder object gets warmer it gains kinetic energy.
What is heat energy measured in?
Joules (J).
How much temperature changes depends on what?
The material it is made from (when the bonds are weak a small transfer of heat can result in a lot of extra vibration causing a large rise in temperature) and the number of particles in the object (if heat energy is shared between a large number of particles, the average increase in kinetic energy in each particle will be small).
What are the different units of measure for temperature?
Degrees Celsius and Kelvin (k).
What does the degrees celcuis define as 0 degrees and 100 degrees?
0 degrees is the point water freezes and 100 degrees is the point water boils.
What is normal body temperature and room temperature?
Normal body temperature is usually 36 or 37 degrees and normal room temperature is usually 20 degrees
What does the Kelvin scale define as 0K or absolute zero?
The point where the particles completely stop moving this is also known as -273 degrees.
What do you do to convert degrees to kelvin?
Just add 273.
What does temperature measure?
Temperature is a measure of the average kinetic energy of the particles in an object.
How is temperature measured?
Temperature is measured using a thermometer, there are lots of different types.
