Chap. 11 Thermal energy transfers Flashcards
Thermal conduction-
the transfer of thermal energy by the vibration of molecules
generally, what materials are better as conductor?
Metals
generally, what materials are better as insulators?
non metals
how does conduction in non-metals occur?
when heated, the particles are vibrating much more than the cold ones. These vibrating particles collide and share energy with their neighbours. This transfers heat to the cold particles.
how does conduction in metals occur?
Metals contain delocalised electrons that are free to move. Therefore heat is able to move faster and more easily through it.
how are liquids and gases as conductors and why?
Liquid and gas particles don’t transfer vibrations as easily, and are poor conductors
What are the 3 types of thermal energy transfers?
Conduction. convection, and radiation
convection-
thermal energy in liquids and gases
for convection: energy is transferred through material from a warmer to colder place by the ___ of the material itself
movement
what happens to air’s density when it is heated?
it decreases
cold air ___ and hot air ____
sinks; rises
radiation-
the only form of thermal energy transfer which does not need a medium to travel through
infrared radiation-
radiation we cannot see, but feel as heat
a surface that reflects infrared radiation is a _____
poor absorber
a surface that is a good absorber of infrared radiation is a ____
good emitter
all objects ___ and ___ radiation from their surroundings
emit and absorb
the ___ the more radiation it emits each second
hotter
insulating something-
keeping energy in something that is hotter than its surroundings
what 4 things does a car cooling system use?
Specific heat capacity: water absorbs thermal energy
Convection: convection current flows in the water
Conduction: thermal energy is conducted to all parts by metal fins
Radiation
