Energy

Question 1

Name 4 energy stores

Answer 1

1. Kinetic
2. Gravitational potential
3. Magnetic
4. Electrostatic

Question 2

3 ways energy can be transferred in a system?

Answer 2

1. In or out the system
2. To and from different objects
3. To and from different stores

Question 3

What is a closed system

Answer 3

Matter nor energy can leave or enter

Question 4

What is always the net change in the total energy of a closed system?

Answer 4

0

Question 5

2 ways energy can be transferred and how?

Answer 5

1. Heating - energy is transferred into the water’s thermal energy store from the kettle’s heating element
2. Doing work - transfers energy by providing a force

Question 6

Equation for kinetic energy store?

Answer 6

E = 1/2mass x velocity^2

Question 7

How does kinetic energy transfer?

Answer 7

When an object speeds up, energy is transferred to this store, when an object slows down, energy is transferred away

Question 8

Equation for GPE

Answer 8

E = mass x gravitational field strength x height

Question 9

How do falling objects transfer energy?

Answer 9

Energy from the object’s GPE store is transferred into the object’s kinetic store

Question 10

Why does energy lost from GPE = energy gained in kinetic not always work for falling objects?

Answer 10

Air resistance causes some energy to be transferred to other energy stores

Question 11

Equation for elastic potential energy?

Answer 11

E = 1/2spring constant x extension^2

Question 12

Equation for specific heat capacity?

Answer 12

Change in energy = mass x specific heat capacity x temperature change

Question 13

What is specific heat capacity?

Answer 13

The amount of energy needed to heat 1kg of an object up by 1 degree Celsius

Question 14

What is the conservation of energy principle?

Answer 14

Energy can be transferred, stored or dissipated, but never created or destroyed

Question 15

How can energy be dissipated?

Answer 15

In a phone, energy from the battery’s chemical store is usefully transferred, whilst some is transferred to the thermal energy store

Question 16

What is wasted energy?

Answer 16

Energy being stored in a way that is not useful

Question 17

Describe energy transfer in a closed system of a spoon in soup.

Answer 17

Assuming a lid is a perfect insulator, energy is dissipated from the thermal energy store of the soup to the useless thermal store of the spoon, cooling the soup down, although no energy has left the system

Question 18

Equation for power?

Answer 18

P = energy transferred (or work done) / time

Question 19

What does power mean?

Answer 19

Rate of energy transfer

Question 20

How does conduction work?

Answer 20

1. Energy is transferred to an object’s thermal energy store by heating
2. Particles in this part of the object begin vibrating and collide with adjacent particles, transferring to kinetic energy stores

Question 21

What is thermal conductivity?

Answer 21

How quickly energy is transferred through an object

Question 22

How does convection work?

Answer 22

1. Energy is transferred to a liquid/ gases thermal energy store by heating
2. The faster moving particles then move further apart, reducing density
3. The less dense substance, then moves above the denser, cooler substance

Question 23

How do radiators heat rooms?

Answer 23

1. Energy is transferred from the radiator to nearby air particles by conduction
2. Air particles by the radiator move quicker and spread out, reducing density and moving above the denser air
3. Colder takes the place of the hot air and a convection current is created

Question 24

How do lubricants reduce unwanted energy transfer?

Answer 24

Lubricants reduce friction, which can cause some energy to be dissipated to an object’s thermal store

Question 25

4 ways energy loss can be prevented in houses?

Answer 25

1. Cavity walls - have an air gap to reduce energy loss through conduction out of the house 2. Loft insulation - reduce convection currents in a loft 3. Double glazed windows - air gap between two windows reduces conduction 4. Draught excluders - reduce convection around doors and windows

Question 26

Efficiency equation?

Answer 26

Efficiency = useful energy output/ total energy input

Question 27

What does efficiency mean?

Answer 27

How much energy is transferred usefully

Question 28

Example of a 100% efficient device?

Answer 28

Electric heater

Question 29

Non renewable energy sources used in transport?

Answer 29

1. Petrol/ diesel 2. Coal

Question 30

Renewable energy sources used in transport?

Answer 30

Biofuel

Question 31

Non renewable energy sources used for heating

Answer 31

1. Natural gas 2. Coal 3. Electric heaters

Question 32

Renewable energy sources used for heating?

Answer 32

1. Geothermal 2. Solar water heaters 3. Bio fuel

Question 33

4 Disadvantages of wind power?

Answer 33

1. Spoil the view 2. Noise pollution 3. Unreliable - must be windy 4. Impossible to increase supply in high demand

Question 34

3 Disadvantages of solar cells?

Answer 34

1. Expensive to manufacture 2. Can't increase supply in high demand 3. Only work in the daytime

Question 35

2 Disadvantages of geothermal?

Answer 35

1. Not many suitable locations 2. Expensive to build a plant

Question 36

3 Disadvantages of hydroelectric?

Answer 36

1. Flooding valleys destroys habitats 2. Can ruin landscapes 3. Initial costs are high

Question 37

3 Disadvantages of waves?

Answer 37

1. Disturbed sea bed and habitat destruction 2. Hazard to boats 3. Unreliable - waves rely on wind

Question 38

Disadvantages of tidal barrages?

Answer 38

1. Preventing access to boats 2. Ruins habitats 3. Spoils view

Question 39

Disadvantages of bio fuels?

Answer 39

1. Only carbon neutral if plants are grown at the same rate as burning 2. Cannot respond to immediate energy demands 3. Plants for bio fuels means less space for people to grow foods

Question 40

Advantages of non renewable energy?

Answer 40

1. Reliable 2. Can increase supply in times of high demand 3. Running costs are low

Question 41

4 Environmental disadvantages of non renwable energy?

Answer 41

1. Greenhouse effect 2. Sulphur dioxide causes acid rain which damages wildlife 3. Oil spills kill marine life 4. Nuclear waste is very dangerous

Question 42

Why does the UK aim to be more renewable?

Answer 42

Pressure from other countries and the public

Question 43

Why is renewable use limited?

Answer 43

1. Scientists can't make people change 2. Renewable plants mean higher costs for the population through tax 3. Ethical arguments of making people live next to wind farms