Phy Temperature And Heat Ch11 Heat

Front 1

What is the definition, unit and symbol of heat?

Back 1

Heat is a form of energy that causes a rise in temperature when added or fall when withdrawn. Its unit is joules (J). Its symbol is Q.

Front 2

What is the definition, unit and symbol of heat capacity?

Back 2

Heat capacity of an object is the heat required to change its temperature by 1 kelvin. Its unit is J K-1. Its symbol is C.

Front 3

What is the formula of heat capacity?

Back 3

Front 4

What is the definition, unit and symbol of specific heat capacity?

Back 4

Specific heat capacity of a substance is the amount of heat energy needed to change 1 kg of a substance by 1 kelvin. Its unit is J kg-1 K-1. Its symbol is C.

Front 5

What is the formula of specific heat capacity?

Back 5

Front 6

What is the definition and unit of latent heat?

Back 6

Latent heat of a substance is thr heat energy required to change its state without a change in temperature. Its unit is joules (J).

Front 7

What is the definition and unit of specific latent heat?

Back 7

Specific latent heat of a substance is the amount of heat energy required to change the state of 1 kg of the substance without a change in temperature. Its unit is J kg-1.

Front 8

What is specific latent heat of vaporisation?

Back 8

Specific latent heat of vaporisation of a substance is the amount of heat energy required to change 1 kg of the substance from a liquid to a gas without a change in temperature.

Front 9

What us specific latent heat of fusion?

Back 9

Specific latent heat of fusion of a substance is the amount of heat energy required to change 1 kg of the substance from a solid to a liquid without a temperature change.

Front 10

What is the formula of specific latent heat?

Back 10

Front 11

Name 2 heat pumps.

Back 11

Perspiration (sweating) and refrigerator.

Front 12

How does perspiration work?

Back 12

The body releases water on the skin, causing the water to absorb the heat from the body causing it to change state, without a change in temperature (latent heat).

Front 13

How does the refrigerator work?

Back 13

1. High-pressure liquid (HPL) enters an expansion mechanism. The mechanism lowers the pressure of the liquid by moving its particles apart. The liquid becomes a low-pressure liquid (LPL).

2. Liquids dont like being at low pressure, causing the LPL to change state to a low-pressure vapour (LPV). To do this it needs energy, where the heat energy is absorbed from inside the fridge.

3. The LPV then enters a compressor that forces the vapours particles to come closer together. Changing it to a High-Pressure Vapour (HPV).

4. Vapours dont like being at high pressure, causing it to change to a HPL, which releases heat energy at the back of the fridge.

5. The HPL re-enters the expansion mechanism and the cycle begins again.

Front 14

What is conduction?

Back 14

Conduction is the transfer of heat in a solid by passing kinetic energy from molecule to molecule.

Front 15

What is convection?

Back 15

Convection is the transfer of heat energy by the circulation of the heated parts of a liquid or gas.

Front 16

What is radiation?

Back 16

Radiation is the transfer of heat energy as electronagnetic (EM) waves, without the need of a medium.

Front 17

What is the solar constant?

Back 17

The amount of energy striking 1 m2 of the earths atmosphere every second.

Front 18

What is u-value?

Back 18

The u-value of a material is the amount of heat energy that can be transmitted across 1 m2 of its surface every second, so long as there is a temperature difference of 1 K each side of the material.