Thermal Energy Flashcards
What is a system
An object or group of objects
Energy stores
Thermal
Elastic
Kinetic
Gravitational
Chemical
Electrostatic
Nuclear
Magnetic
How do energy transfers happen
Energy transfers happen because of: forces doing work, a flow of an electrical current, heating, light radiation, and sound waves
Internal energy
the total kinetic and potential energy of all the particles
SHC definition
energy (in J) needed to increase the temperature of 1 kg
of a substance by 1 0C (or Kelvin can be used too)
Accurate data
Close to true value
Precise data
Repeated measurements with low spread around mean
Reproducible data
Other person get same results with same equiptment and methods
Repeatable data
Same person can get the same result with the same equipment and method
Random error
Measurements spread around a mean value. Reduced with repititions and means
Systematic error
measurement is always too high or too low
Zero error
Instrument reads a value when it should say 0
How to reduce unwanted energy transfer
lubrication (when parts move) and
thermal insulation
Thermal conductivity
rate at which energy is transferred when there is a difference in temperature either side of it
Factors affecting rate of cooling of a building
thickness of the building’s walls and the thermal conductivity of its insulation
Specific latent heat
The specific latent heat of a substance is the amount of energy (in J) required to change the state of 1 kg of the substance with no change in temperature.
Fusion = solid to liquid
Vaporisation= liquid to gas
