07. P2 Energy Transfer by Heating

Question 1

What property describes how rapidly heat moves through a solid?

Answer 1

Thermal Conductivity

Question 2

Explain why birds fluff up their feathers in winter.

Answer 2

Fluffing feathers traps air, air is a good insulator so less energy is as lost through conduction.

Question 3

A metal and a wooden pole have been out all night on a frosty evening, in the morning you pick one up with your left hand and one with your right. Which one feels coldest and why?

Answer 3

Metal feels coldest as it is a good conductor so conducts more energy away from your hand each second. So feels colder, but BOTH are actually at the same temperature.

Question 4

What is the name given to a poor conductor?

Answer 4

Insulator

Question 5

State the name given to thermal energy transfer in the form of a wave?

Answer 5

Infrared radiation

Question 6

How does the temperature of the object affect the amount of IR radiation given out?

Answer 6

Hotter = more radiation given out per second

Question 7

What objects are the best emitters of IR radiation?

Answer 7

Black and Matt objects

Question 8

What objects are the best absorbers of IR radiation?

Answer 8

Black and Matt objects

Question 9

Which objects are the best reflectors of IR radiation?

Answer 9

White and shiny

Question 10

If you pour a freshly boiled cup of tea. Explain why it cools down at a quicker rate just after it has been freshly boiled rather than 5 minutes later.

Answer 10

The temperature difference between the room and the cup of tea is at its greatest immediately after pouring it.

Question 11

List the different places heat is lost from a house.

Answer 11

Roof, Walls, floor, windows, Draughts

Question 12

State what can be added to a house to reduce heat loss through the house?

Answer 12

Loft insulation

Question 13

State what can be added to a house to reduce heat loss through the walls?

Answer 13

Cavity wall insulation

Question 14

State two things which can be added to a house to reduce heat loss through windows?

Answer 14

Double glazing and curtains

Question 15

Describe how loft insulation reduces heat loss through the roof.

Answer 15

Loft insulation has air pockets trapped in it. Air is a good insulator so reduces heat loss by conduction

Question 16

Describe how cavity wall insulation reduces heat loss through the roof.

Answer 16

Cavity wall insulation has air pockets trapped in it. Air is a good insulator so reduces heat loss by conduction

Question 17

How does a sheet of aluminium foil between a radiatior panel and wall help reduce energy losses?

Answer 17

Radiation from the radiator is reflected away from the wall and so reduces the rate of energy transfer into the wall by radiation

Question 18

How do double glazed windows help to reduce energy losses?

Answer 18

The air gap between the two panes of glass reduces heat loss by conduction, as air is a good insulator.

Question 19

The energy transfer per second through a layer of insulating material depends on what three factors?

Answer 19

1) Temperature difference, 2) material thickness, 3)thermal conductivity of the material

Question 20

Why do rescue teams use light-coloured shiny blankets when treating someone?

Answer 20

To keep people warm - light, shiny surfaces reflect the heat emitted from the body back to the person, and also emit less radiation than if it was a dark, matt surface

Question 21

What factors determine the rate of thermal energy transfer?

Answer 21

Temperature Difference, Thickness of Material, Thermal Conductivity of material.