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30 Cards in this Set
- Front
- Back
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Why does heat energy always flow?
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It flows from hot to cold until the temperature is the same.
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What states does convection work in?
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Liquids and gases.
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Why do most fluids expand when heated?
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Because the particles move about more taking up more space.
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What does convection do?
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Convection (circulation) currents transfer thermal energy from the hotter parts,to the cooler parts.
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What do fluids do in convection (circulation) currents?
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When they are heated, they rise (heating makes them less dense) Then they fall where they cool down making them more dense.
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What is radiation?
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It is when an object that is hotter than its surrounding gives off heat onto the other objects around it.
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Do black,dull surfaces emit and absorb heat?
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Yes.
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Do shiny,white surfaces emit and absorb heat?
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They reflect heat and are poor at emitting heat.
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What is the 'payback time' equation?
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payback time=installation cost/fuel saving
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Why does heat energy always flow?
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It flows hot to cold, until the temperature is the same.
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Do cold objects have cold energy?
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No, they have less heat energy.
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What state does convection work in?
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Liquids and gases.
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What happens in convection (circulation) currents?
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The fluids rise, they are heated, then they fall where they cool down. This makes them denser.
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What does convection do?
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It transfers thermal energy from the hotter parts to the cooler parts.
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Why do most fluids expand when heated?
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The particles move about more taking up more space.
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What makes fluids denser?
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By heating them or cooling them.
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What is radiation?
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When an object that is hotter than its surroundings gives off heat onto the other objects around it.
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Do black,dull surfaces emit and absorb heat?
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Yes.
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Do shiny,white surfaces emit and absorb heat?
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They are poor emitters of heat and reflect heat.
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What is the pay back time equation?
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Payback time (years) = installation cost/fuel saving
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What are U-values?
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They measure how effective a material is as an insulator, the lower the u-value, the better the material is as an insulator.
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The hotter the object is...
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the more infra red radiation it emits.
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Where does evaporation happen?
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In liquids.
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When does evaporation happen?
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It will evaporate at any temperature as long as there is energy, this energy can come from sunlight.
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Does temperature affect evaporation?
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Yes, as the temperature increases, the evaporation speeds up.
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What factors affects evaporation?
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The surrounding temperature, surface area, energy provide and the type of liquid-viscosity.
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What is specific heat capacity?
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It is the energy required to raise the temperature of 1KG of a material by 1◦C.
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What is the specific heat capacity?
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E=m x c x Ѳ
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What is specific latent heat?
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It is the amount of energy needed to change the state of 1KG of a material.
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What is the specific latent heat formula?
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It is energy=mass x specific latent heat
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