Lesson 2:Heat Transfer/ Conduction

Question 1

What is the difference between “heat” and “temperature?”

Answer 1

• Heat: Thermal energy stored in all objects.
• Temperature - Average kinetic energy of molecules

Question 2

What is “heat” measured in?

Answer 2

• Heat = Thermal energy
• Heat measured in Joules (J)

Question 3

What is the standard unit for temperature?

Answer 3

• Kelvins (K)

Question 4

Why is temperature the measure of average kinetic energy of particles?

Answer 4

• This is because when you heat something, particles move quicker.

Question 5

What does thermal energy depend on?

Answer 5

• Thermal energy depends on the number of particles.
  pot of tea has more thermal energy than cup of tea

Question 6

What is an “insulator”?

Answer 6

• An insulator is a material that doesn’t conduct well.

Question 7

What are the 2 types of conduction?

Answer 7

• Thermal conduction
• Electrical conduction

Question 8

Why are metals good conductors of heat and electricity?

Answer 8

• They have delocalised electrons that can transfer thermal energy through the material.

Question 9

Why are some metals better conductors than others?

Answer 9

• Some metals have more delocalised electrons than others.

Question 10

Why does wood feel warmer than metal when they are both at the same temperature?

Answer 10

• The wood is an insulator of your body’s heat.
• The metal is a conductor of your body’s heat.
• So makes it feel cold*

Question 11

What is meant by “direction of heat transfer?”

Answer 11

• This means that heat is always transferred from a hot area to a cold area.

Question 12

What is the direction of heat transfer for foods in the fridge?

Answer 12

• The food has thermal energy.
• This is transferred to the cold fridge.
• This makes food cold, preserving it.

Question 13

What is meant by thermal equillibrium?

Answer 13

• Thermal equillibrium means an object isn’t gaining or losing thermal energy.

Question 14

What is room temperature?

Answer 14

• Around 27 degrees celcius.

Question 15

What is the direction of heat transfer for a 46 degree cup of tea?

Answer 15

• The hot tea transfers energy to the surroundings.

Question 16

What is the direction of heat transfer for ice to melt?

Answer 16

• The warmer surroundings transfer energy to the 0 degree ice cube.

Question 17

Why does ice melt faster on a metal to wood?

Answer 17

• The materials transfer heat from surroundings to ice by conduction.
• Metal is a better conductor so transfers energy quicker.

Question 18

The higher the thermal conductivity of a material the higher the………………………….

Answer 18

• Energy transferred by conduction across the material.

Question 19

What 2 factors affect the rate of cooling down of a building?

ie. amount of thermal energy that is lost

Answer 19

• Thermal conductivity of walls.
• Thickness of the walls.

Question 20

How does heat escape from walls?

Answer 20

• Cavity in between 2 walls.
• To reduce, fill with low conductivity foam material (insulation.)

Question 21

How can we reduce heat that escapes through windows?

Answer 21

• Use double - glazing
• Has a lower thermal conductivity.

Question 22

What can you do to reduce the rate of thermal energy transfer in walls other than using low conductivity materials?

Answer 22

• Use thicker walls to reduce rate of thermal energy transfer.