thermal energy Y9 Flashcards
radiation
-all objects emit infrared radiation
-radiation does NOT need paticles
-dark matt surfaces are the best absorbers and emitters of radiation
-shiny surfaces reflect radiation
Thermal energy
-heat transfers from a hotter object to a colder object
-heat transfer will stop when both objects are the same temp
-the surface area and material affect the thermal energy rate
-there are 3 ways in which heat is transferred: radiation, conduction, convection
conduction
-conduction occurs when particles in a solid are heated
-a metal is a conductor of heat
-plastic or a newspaper is a poor conductor or insulator
how does conduction happen?
as particles are heated, they gain energy and vibrate more. as they vibrate, they collide and so transfer energy to the next particle.
convection
-convection occurs when particles in a fluid (liquid or gas) are heated.
-the particles gain energy, they move around more and so take up more space and become less dense.
- less dense fluid will rise and be replaced by a denser fluid.
heat
-heat is the amount of thermal energy stored in an object.
-it is measured in Joules (j)
the greater the mass, the more particles.
temperature
temperature is a way that we can measure thermal energy in a substance.
-it is measured in degrees Celsius ( oC )
what direction does heat energy always transfer from?
from the warmer object to the cooler object
what type of heat transfer occurs in solids?
conduction
why are metals good conductors?
they have free electrons
what is the name given to a poor conductor?
an insulator
what is meant by a fluid?
liquid or a gas- something that flows
explain how convection happens in a fluid
heated particles move faster, become less dense, rise, and then are replaced.
what group of waves does infrared sit in?
electromagnetic spectrum
what objects are good absorbers of radiation?
matt black objects
