Chapter 15 - Quantity Of Heat & Heat Transfer

Question 0

Define:

Specific Latent heat capacity (c)

Answer 0

(c) is the heat energy needed to change the temperature of 1Kg of that substance by 1K

Question 1

Define:

Heat Capacity

Answer 1

The heat energy needed to change its temperature by 1K(1*C)

Question 2

Define:
Latent heat (L)

Answer 2

(L) is the heat energy needed to change its state without a change in temperature

Question 3

Define:

Specific latent heat (l)

Answer 3

(l) is the amount of heat energy needed to change the state of 1Kg of that substance without a change in temperature

Question 4

Define:

Specific latent heat of fusion

Answer 4

Is the amount of heat energy needed to change 1Kg of that substance from a solid to a liquid without a change in temperature

Question 5

Define:

Specific latent heat of vaporisation

Answer 5

Is the amount of heat energy needed to change 1Kg of that substance from a liquid to a gas without a change in temperature

Question 6

Define:

Solar constant

Answer 6

The average amount of the sun’s energy falling per second perpendicularly on 1 metre squared of the earths atmosphere ( 1.35 kW m(-2) )

Question 7

Define:

U-value

Answer 7

The amount of heat energy conducted per second through 1m(2) of that structure when a temperature difference of 1*C (1K) is maintained between its ends

Question 8

State:

The three states of matter

Answer 8

Solid

Liquid

Gas

Question 9

State:

The relationship between the U-valve of a structure and how good an insulator it I

Answer 9

Bad insulator=high U-valve (good conductor)

Good insulator=low U-valve (bad conductor

Question 10

Explain:

Conduction

Answer 10

The movement of heat energy through a substance by the passing on of molecular vibration from molecule to molecule. There is no overall motion of the substance.

Question 11

Explain:

Convection

Answer 11

Is the transfer of heat through a fluid by means of circulating currents of fluid caused by the heat

Question 12

Explain:

Radiation

Answer 12

Is the transfer of heat energy from one place to another in the form of electromagnetic waves

Question 13

Explain:

What is Heat pumps

Answer 13

Transfers energy from a cooler region to a warmer one.

The circulating liquid has a high specific latent heat of vaporisation and a low boiling point.

Question 14

Explain:

How a heat pump works

Answer 14

The liquid is pumped around a closed circuit.
On reaching the expansion valve, pressure drops, the liquid vaporises.
When the vapour reached the compressor, it’s pressure is increased and it turns back into a liquid.
This heat is given off to the surroundings from the black pipes and cooling find at the back of the fridge.

Question 15

Explain:

Perspiration

Answer 15

Perspiration is mainly water. As this water evaporates, it takes its latent heat from you and you cool down

Question 16

Explain:

Domestic hot water and heating systems

Answer 16

Convection

Question 17

Explain:

Solar heating

Answer 17

Heat water through glass in pipes

Heat a solar panels photocells turning into electrical energy