P7

Question 1

What is chemical energy

Answer 1

Energy stored in the bonds of compounds

Question 2

What is thermal energy

Answer 2

Energy relating to temperature, or a change in temperature

Question 3

What is kinetic energy

Answer 3

Energy an object has due to motion

Question 4

What is graviational energy

Answer 4

The energy an object has due to gravity

Question 5

What is elastic energy

Answer 5

The mechanical potential energy of a material as work is performed on it

(Energy associated with deforming metals)

Question 6

What is nuclear energy

Answer 6

Energy associated with nuclear fusion or fission

Question 7

What is electrostatic energy

Answer 7

Energy associated with the distortion of electric fields and charges

Question 8

What i magnetic energy

Answer 8

Energy associated with the separation or joining if magnetic poles

Question 9

What is non-zero speed

Answer 9

The speed of any object with kinetic energy

Question 10

How is GPE calculated

Answer 10

Mass × gravity × height

Question 11

How is kinetic energy calculated

Answer 11

1/2mv²

Question 12

How is thermal energy calculated

Answer 12

Mass × SHC × ∆temp

SHC is the energy needed to increase an object by 1°C or 1K

Question 13

How is elastic energy calculated

Answer 13

1/2kx²

K= spring constant
X = extension

Question 14

How is energy transferred

Answer 14

Mechanically → using forces
Electrically → using current
Heating by particles
Heating by radiation
.

Question 15

In what way is kinetic energy transferred

Answer 15

Mechanically

Question 16

How is efficiency of energy transferr calculated

Answer 16

(useful output ÷ output energy)×100

(Useful output ÷ input)×100

Question 17

How are thermal and chemical energy transferred

Answer 17

By heating of particles

Chemical energy can also be transferred mechanically

Question 18

How do electromagnetic waves transfer energy

Answer 18

Heating by radiation
The greater their frequency, the greater their energy transfer

Question 19

Describe the changes in energy when falling down a steep slope

Answer 19

Gravitational energy is transferred mechanically to kinetic energy

Then mechanical again kinetic energy is transferred to chemical energy

Question 20

What is the conservation of energy

Answer 20

Energy cannot be created or destroyed
Energy can only be transferred between stores

Question 21

What happens during the transfer of energy in a closed system

Answer 21

The increase of energy in one store will be equal to the decrease in another store

Question 22

Where does an electric current transfer energy from

Answer 22

From a chemical store in a battery
From a chemical or nuclear store, used to power the mains elesctricity

Question 23

What are power ratings

Answer 23

Ratings given to appliances to show how much energy they will transfer faster

Question 24

Whats an advantage to using high energy rated appliances

Answer 24

They will complete a task faster, but at a higher price

Question 25

How do you calculate electrical work done

Answer 25

Work done = power × time

Question 26

What is electrical work done measured in

Answer 26

kWh (killowatt hour)

Question 27

How do you transfer joules to kWh

Answer 27

1kWh = 3.6×10⁶ J 1kW = 1000J Hour = 3600s

Question 28

How do you calculate the cost of an appliance

Answer 28

Electrical work done × current rate

Question 29

What do electrical appliances do (energy transfer)

Answer 29

Transfer energy electrically from chemical stores

Question 30

How is energy transferred when current flows through a wire

Answer 30

When current flows through a wire the wire heats up This means energy is transferred to a chemical store and is wasted

Question 31

Why cant appliances such as motors be 100% efficient

Answer 31

As energy is transferred to the thermal store

Question 32

In what systems is chemical energy lost to the surroundings

Answer 32

In all mechanical systems

Question 33

Why is electricity transferred at a high voltage but low current

Answer 33

To reduce the heat loss to the environment (Through heating of particles)

Question 34

What is energy diserpation

Answer 34

Loss of energy to the surroundings

Question 35

How is energy loss reduced in mechanical systems

Answer 35

Using lubrication reduces friction, and therefore energy loss is reduced

Question 36

How is heat loss by heating of particles reduced

Answer 36

By using insulation (Insulating materials)

Question 37

What is thermal conductivity

Answer 37

A measure of how quickly energy is transferred through a material The thermal conductivity of a material is fixed and doesnt change based on its mass The higher the thermal conductivity the faster energy is transferred

Question 38

Why are houses built using materials with a low thermal condictivity

Answer 38

Prevents hot air entering and making the house hot during summer Prevents hot air leaving the house during winter It reduces the transfer of heat to the surroundings

Question 39

What is a cavity wall

Answer 39

A method of insulating a building Insulating material (low thermal conductivity) is placed between the inner and outer walls of a house

Question 40

How does loft insulation help reduce heat loss

Answer 40

As hot air rises it is important to have good loft insulation This will reduce the heat loss to the surroundings

Question 41

How does double glazing reduced a houses thermal conductivity

Answer 41

As that is placed between the panes of glass has a low thermal conductivity Glass also has a relatively low thermal conductivity

Question 42

How does increasing the thickness of a wall affect energy transfer

Answer 42

The thicker the wall the slower the transfer of energy Heat is transferred by conduction at a slower rate There is a greater distance the energy has to be moved

Question 43

What is conduction

Answer 43

Energy transferred between neighbouring atoms or molecules

Question 44

Why are igloos warm

Answer 44

Although ice is a 'cold' material, they have a low thermal conductivity, and therefore can trap heat inside

Question 45

How do you calculate the efficiency of energy transfer

Answer 45

Efficiency = (useful output energy ÷ input energy) × 100

Question 46

What is a sankey diagram

Answer 46

A diagram drawn showing total energy, and how much is wasted or useful The size of an arrow represents the amount of energy transferred

Question 47

How are sankey diagrams drawn

Answer 47

You need to use a scale so that the size of the arrow is proportional to the energy

Question 48

How do you improve efficiency

Answer 48

Use insulation. Use materials that reduce unwanted energy transfer Use technology to produce better devices, e.g LEDs which give of little heat