science chapter 10: transfer of heat energy and its effects

• The SI unit of temperature is kelvin (K).
• In general, solids, liquids, and gases expand when heat energy is absorbed and contract when heat energy is given out.
• Thermal expansion results in a change in volume, and therefore the density of the substance.
• Heat energy is transferred from a region of higher temperature to a region of lower temperature.
• Thermal energy absorbed causes solids to expand.
• Thermal energy released causes solids to contract.
• A thermometer works due to the absorption of thermal energy from the surroundings.
• During contraction, volume decreases, mass remains constant, and density increases.
• During expansion, volume increases, mass remains constant, and density decreases.
• Gases expand the most when heated, as particles are able to move about freely, and thus able to move further apart from each other the most.
• Mass remains constant while volume increases, causing the density to decrease.
• Black and dull surfaces are good and fast absorbers of thermal radiation and good and fast radiators/emitters of thermal radiation.
• White is a good reflector and a poor absorber of thermal radiation, making it easier to keep the building cool.
• Conduction and convection cannot take place in a vacuum.
• Shiny and smooth surfaces are poor and slow absorbers of thermal radiation and poor and slow emitters of thermal radiation.
• Global warming is caused by the increase in the amount of carbon dioxide in the atmosphere, which is contributed to by both natural and man-made causes.
• Shiny and smooth surfaces are good reflectors of thermal radiation.
• If the surrounding temperature is higher than the object, then the object is an absorber.
• Two natural causes of global warming are volcanic eruptions and organisms, which release carbon dioxide.
• If the surrounding temperature is lower than the object, then the object is a radiator.
• Black surfaces absorb thermal energy faster than white surfaces.
• Land and sea breezes are caused by convection.
• Radiation transfers thermal energy in the form of waves ( infra-red ).
• Dull, black and rough surfaces are good radiators, good absorbers, and poor reflectors.
• The hotter the body, the higher the rate of radiation.
• Black surfaces also releases thermal energy faster.
• Transfer of thermal energy process that does not require a medium.
• The land absorbs heat energy from the sun and warms up faster than the sea.
• Shiny, silvery and smooth surfaces are poor radiators, poor absorbers, and good reflectors.
• Hot air rises from the land, and a cool sea breeze blows in to take its place.
• A dark and rough surface is a good radiator and absorber of heat.
• During the day, the land is hotter than the sea.
• The rate of radiation depends on the nature of surface, total surface area of body, and surface temperature.
• The cooled air is denser and therefore sinks.
• Heat can radiate across vacuum.