Flashcards
Physics-Thermal Effects
Cards in this deck (25)
- 1SolidA solid has a fixed shape and volume. Particles are held closely together by strong forces of attraction called bonds. They vibrate backwards and forwards but cannot change positions.
- 2LiquidHas a fixed volume but can flow to fill any shape. The particles are close together and attract each other, but the particles vibrate vigorously and cannot be held in fixed positions.
- 3GasHas no fixed shape or volume and quickly fills any space available. Particles are well spaced out and virtually free of attractions. Move at high speed and collide with each other.
- 4And here is a fun fact for your enjoyment...The hotter a material is, the faster it's particles move, and the more internal energy it has.
- 5Calculating Kelvin temperatureTemp. In °C +273
- 6How does temperature effective than particle movement?As particles heat up they gain kinetic energy and move fast, as they cool down they loose kinetic energy and move more slowly.
- 7Liquid in glass thermometersNormally filled with alcohol or mercury. Nearly all liquids expand slightly when heated.
- 8SensitivityThe narrower the tube, the higher the sensitivity. The sensitivity also depends on the liquid used, eg. a mercury thermometer must have a narrower tube than an alcohol thermometer as it easy pants less when heated.
- 9RangeMercury freezes at -39°C, and alcohol freezes at -115°C. Mercury typically has a much higher upper limit of around 500°C.
- 10ResponsivenessSome thermometers respond more quickly to a change in temperature than others. A thermometer with a larger bulb, or thicker glass round the bulb, is less responsive as it takes longer for the alcohol or mercury to heat up.
- 11LinearityAlthough alcohol and mercury thermometers must agree at certain points, the email pension of liquids is not linear so there can be some disagreements below 0 and above 100°C.
- 12Thermal ExpansionWhen some concrete or a steel bar is he heated it's volume will increase slightly. The particles vibrate more quickly and these vibrations take up more space causing the material to expand in all directions. If the temperature falls the particles vibrate less and the material contracts.
- 13Thermal ConductionIf a metal bar is heated, thermal energy is transfered from the hot end to the cold end as the faster particles pass on their extra motion to particles all along the bar. This is thermal conduction.
- 14More thermal energy is transfered every second if...1. The temperature difference across the ends of the bar is increased.
2. The cross sectional area of the bar is increased.
3. The length of the bar is reduced. - 15Are metals good thermal conductors?Yes, they are the best.
- 16Are non-metals and liquids good conductors?No, they are good insulators but poor conductors.
- 17Are gases good conductors?No, they are the poorest conductors.
- 18ConvectionConvection occurs in liquids and gases. The warm air rises, then the air cools, and the cool air sinks, then it goes back to the radiator and is heated again. Examples of convection are radiators, fridges, and water rising off the sea on a hot day.
- 19Thermal RadiationOn earth we are warmed by electromagnetic waves which are absorbed by things, which heat up.
- 20EmittersBlack=best
Shiny=worst - 21ReflectorsShiny= best
Black= worst - 22AbsorbersBlack= best
Shiny= worst - 23How to evaporate a liquid more quickly.1. Increase the temperature.
2. Increase the surface area.
3. Reduce the humidity.
4. Blow air across the surface. - 24Energy transferredEnergy transfered= mass × specific heat capacity × temperature change
E= mc t - 25Energy transferedEnergy transfered= mass × specific latent heat
E= mL
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- Flashcards on Physics-Thermal Effects, created by abigaildallas on 01/01/2015.
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