P1.1 The transfer of energy

Question 1

What do U values measure?

Answer 1

U-values measure the effectiveness of a material as an insulator in buildings. The lower the U-value is, the better the material is as a heat insulator.

Question 2

What is Kinetic theory?

Answer 2

The kinetic particle theory explains the properties of the different states of matter. The particles in solids, liquids and gases have different amounts of energy.

Question 3

What is the equation for specific heat capacity?

Answer 3

E = m × c × θ
E is the energy transferred in joules, J
m is the mass of the substances in kg
c is the specific heat capacity in J / kg °C
θ (‘theta’) is the temperature change in degrees Celsius, °C

Question 4

What do conduction, convection and radiation do?

Answer 4

Transfer heat from place to place.

Question 5

What’s a good absorber of heat?

Answer 5

Dark matt surfaces.

Question 6

What is conduction?

Answer 6

Heat energy moving through a substance.

Question 7

What are good conductors of heat?

Answer 7

Metals.

Question 8

What are poor conductors of heat?

Answer 8

Non-metals and gases.

Question 9

What are poor conductors of heat called?

Answer 9

Insulators.

Question 10

When does convection occur?

Answer 10

When particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection.

Question 11

When do liquids and gases expand?

Answer 11

When they are heated. This is because the particles in liquids and gases move faster when they are heated than they do when they are cold. As a result, the particles take up more volume.

Question 12

Why does heat rise?

Answer 12

The liquid or gas in hot areas is less dense than the liquid or gas in cold areas, so it rises into the cold areas. The denser cold liquid or gas falls into the warm areas. In this way, convection currents that transfer heat from place to place are set up.

Question 13

What is infrared radiation?

Answer 13

All objects give out and take in thermal radiation. The hotter an object is, the more infrared radiation it emits.

Question 14

What is involved in infrared radiation?

Answer 14

Infrared radiation is a type of electromagnetic radiation that involves waves. No particles are involved, unlike in the processes of conduction and convection, so radiation can even work through the vacuum of space.

Question 15

How is heat lost from a house?

Answer 15

Through the roof, windows, gaps around the doors, walls and floor.

Question 16

How can you reduce heat loss?

Answer 16

Heat loss through windows can be reduced using double glazing. The gap between the two panes of glass is filled with air. Heat loss through conduction is reduced, as air is a poor conductor of heat.

Question 17

What are the arrangement of particles in a solid?

Answer 17

Close together and a regular pattern.

Question 18

What are the arrangement of particles in a liquid?

Answer 18

Close together and random.

Question 19

What are the arrangement of particles in a gas?

Answer 19

Far apart and random.

Question 20

What are the properties of a solid?

Answer 20

They have a fixed shape and cannot flow because the particles cannot move from place to place.
They cannot be compressed or squashed because the particles are close together and have no space to move.

Question 21

What are the properties of a liquid?

Answer 21

They flow and take the shape of their container because the particles can move around each other.
They cannot be squashed