Simplified P1 - Heating Houses & Keeping Homes Warms

Question 1

What direction does Energy ( In the form of heat) Flow?

Answer 1

Energy, when in the form of heat, flows from a warmer body to a colder body.

Question 2

What happens to a warm object when energy flows away from it?

Answer 2

When Energy flows away from a warm object, the object’s temperature decreases.

Question 3

How does a Thermogram show temperature?

Answer 3

A thermogram shows temperature through colours.

Question 4

What areas of a Thermogram represent a hot area, and what areas represent a cold area?

Answer 4

The hottest areas on a thermogram are typically: Pink or white.
The coldest areas on a thermogram are black/dark blue or purple.

Question 5

What happens to the kinetic energy as the temperature increases?

Answer 5

When the temperature of a body increases, the average kinetic energy of the particles increase.

Question 6

What is heat a measurement of, and how is it different to a measure of temperature?

Answer 6

Heat is a measurement of internal energy, it is measured on an absolute scale; Whereas temperature is a measure of hotness on an arbitrary scale, you would not need a thermometer to measure this.

Question 7

What is specific heat capacity?

Answer 7

Specific Heat Capacity is:
The Energy needed to raise the temperature of 1 kg by 1 (Degrees Celsius)
- Specific heat capacity is measured in joules per kilogram Degree Celsius, this measurement differs for different materials.

Question 8

What is the equation for energy transfer by specific heat Capacity?

Answer 8

The Equation is: Energy transferred = mass x specific heat capacity x temperature change

Question 9

Example Question:
Calculate the energy transferred when 30 kg of water cools from 25 Degrees Celsius to 5 Degrees Celsius
Answer on the back of this card

Answer 9

The energy transfer is worked out as followed:
30 x 4200 x ( 25 - 5 ) = 30 x 4200 x 20
= 2,520,000 J or 2520 kJ

Question 10

What is Specific Latent Heat?

Answer 10

Specific Latent Heat is:

• The energy needed to melt or boil 1 kg of the material
• It is measured in joule per kilogram ( J/ Kg) and differs for different materials and each of the changes of state.

Question 11

What happens to an object when it is heated and changes state?

Answer 11

When an object is heated and changes state, energy is transferred, however the temperature remains constant.

Question 12

What is the equation for energy transfer by specific latent heat?

Answer 12

Energy transfer by specific latent heat:

energy transferred - mass x specific latent heat

Question 13

Example Question:
Calculate the energy transferred when 2.5 kg of water changes from solid to liquid at 0 Degrees Celsius.
Answer on the back of this card.

Answer 13

For this question, you would first need to have figured out the specific latent heat.
Energy transferred = 2.5 x 340,000 ( This figure is the specific latent heat )
= 850,000 J or 850 kJ

Question 14

Why is there no temperature change when a substance changes state?

Answer 14

When a substance changes state energy is needed to break the bonds that hold the molecules together, this explains why there is no change in temperature.

Question 15

What does double glazing do?

Answer 15

Double glazing reduces energy loss by conducting.

Question 16

What is double glazing?

Answer 16

Double glazing is where there are two panes of glass with a gap in between, this gap is filled with a gas or contains a vacuum.

Question 17

How does double glazing reduce energy loss?

Answer 17

Double Glazing Reduces energy loss with the gap in between the two panes of the glass, if there is a gas in the panes, the particles are far apart, this makes it very difficult to transfer energy and therefore energy loss is reduced, for example trapped air makes it very difficult for conduction to take place.
If there is a vacuum it means there is an area with no particles, this makes it impossible to transfer energy through conduction reducing energy loss.

Question 18

What is the type of energy transfer that double glazing uses to reduce energy loss

Answer 18

Double glazing reduces energy loss via conduction.

Question 19

How does conduction transfer energy?

Answer 19

Conduction, this transfers energy through the transfer of kinetic energy between particles

Question 20

How does convection transfer energy

Answer 20

Convection transfers energy through this method:
When a gas is heated it expands, this makes it less dense resulting in the gas rising, when the gas rises it will take heat energy with it resulting in energy loss.

Question 21

What is the type of energy transfer that loft insulation reduces in order to reduce energy loss?

Answer 21

Loft insulation reduces energy loss by conduction and convection.

Question 22

How does loft insulation prevent energy loss?

Answer 22

When warm air in the home rises, the energy will be transferred through the ceiling through conduction, however with loft insulation, the air in the loft is warmed by the top of the ceiling and is trapped in the loft insulation, both sides of the ceiling are kept at the same temperature so no energy transfer will take place, without the loft insulation the warm air in the loft will move through via convection and heat the roof tiles resulting in energy loss, the energy will be transferred to the outside via conduction.

Question 23

What are the types of energy transfer that cavity wall insulation reduces in order to reduce energy loss?

Answer 23

Cavity Wall insulation reduces energy loss by conduction and convection

Question 24

How does cavity wall insulation lower energy loss?

Answer 24

Cavity wall insulation reduces energy loss because the air in the foam is a good insulator, and thus air cannot move by convection because it is trapped in the foam, keeping the walls warm and the house warm.

Question 25

Modern insulation blocks feature shiny foil on both sides to reduce energy transfer by radiation, how does it do this?

Answer 25

The shiny foil reflects energy from the home, this keeps the home warm in winter, however in the summer the foil on the other side reflects energy back to keep the home cool in summer.

Question 26

What is one type of energy that can be transferred through a vacuum?

Answer 26

Radiation energy can be transferred through a vacuum, because radiation does not require a material to transfer energy.

Question 27

What is the formula for efficiency?

Answer 27

Efficiency = Useful Energy Output ( x 100 % ) Divided by total energy input.

Question 28

What is payback time?

Answer 28

Payback time is the cost of insulation and the annual savings made by this insulation.

Question 29

What is the formula for payback time?:

Answer 29

Payback time DIVIDED BY annual savings

Question 30

How is energy wasted during heat transfer?

Answer 30

When energy is transferred some of the energy is lost to the surroundings as heat.

Question 31

What is a common type of diagram used to show Energy transformations?

Answer 31

A common type of diagram used to show heat transformations is a Sankey Diagram.