Topic 1 - Energy

Question 1

What is a system?

Answer 1

An object or group of objects

Question 2

What happens when the system changes?

Answer 2

There are changes in the way the energy is stored

Question 3

Name five ways energy stores are changed when embers systems change.

Answer 3

• object projected upwards
• moving object hitting an obstacle
• object accelerated by a contestant force
• vehicle slowing down
• boiling water in a kettle

Question 4

What are the 8 energy stores?

Answer 4

• thermal
• kinetic
• gravitational potential
• elastic potential
• chemical
• magnetic
• electrostatic
• nuclear

Question 5

How is energy transferred?

Answer 5

Mechanically (by a force doing work)
Electrically (work done by moving charges)
Heating
Radiation

Question 6

What is kinetic energy?

Answer 6

Anything that is moving

Question 7

How do you calculate kinetic energy?

Answer 7

1/2 x mass kg x speed (squared) m/s (squared)

Question 8

What is gravitational energy?

Answer 8

Raising an object above ground level rwhuch requires work

Question 9

How do you calculate gravitational potential energy?

Answer 9

Mass x height x gravitational field strength N/Kg

Question 10

What is elastic potential energy?

Answer 10

The amount of energy stored in a stretched spring

Question 11

How do you calculate elastic potential energy?

Answer 11

1/2 x spring constant N/m x extension (squared) m

Question 12

How do you calculate the amount of energy stored in or released from a system as its temperature changes?

Answer 12

Mass x specific heat capacity J/kg*C x temperature change *C

Question 13

What is specific heat capacity of a substance?

Answer 13

Amount of energy required to raise the temperature of one kg of the substance by one degree Celsius

Question 14

Define power.

Answer 14

The rate at which energy is transferred of work is done.

Question 15

How do you calculate power?

Answer 15

• Energy transferred / time

- work done J / time

Question 16

What is an energy transfer one 1 joule per second equal to?

Answer 16

A power of 1 watt

Question 17

What ways can energy be transferred?

Answer 17

Usefully, stored or dissipated

Question 18

Can energy be created or destroyed?

Answer 18

No

Question 19

What is dissipated energy?

Answer 19

Wasted energy as when energy is transferred not all of it is useful

Question 20

Describe energy transfers for a closed system?

Answer 20

Energy can be transferred from the thermal energy store to useless thermal energy store
Energy transfers have occurred within the system but no energy has left the system

Question 21

How do you reduce unwanted energy transfers?

Answer 21

Thermal insulation

Lubrication

Question 22

What happens to an energy transfer when the thermal conductivity of a material is high?

Answer 22

The rate of energy transfer by conduction across the material is higher

Question 23

What is lubrication?

Answer 23

Frictional forces cause some energy to be dissipated

Lubricants reduce frictional forces

Question 24

How does insulation work?

Answer 24

Reduces the rate or energy transfer by heating

• thick walls with low thermal conductivity slow down the theatre if energy transfer
• thermal insulation such as: double glazed glass, fraught excluders, cavity walls

Question 25

How do you calculate efficiency?

Answer 25

Useful output energy transfer / total input energy transfer Useful power output / total power input

Question 26

How can you increase the efficiency of an intended energy transfer?

Answer 26

Insulated objects Lubrication Streamline objects

Question 27

What are the 9 main energy resources on earth?

Answer 27

``` Fossil fuels (coal, gas, oil) Nuclear fuel Biofuel Wind Hydro electricity Geothermal Tides Sun Water waves ```

Question 28

What is a renewable energy source?

Answer 28

One that can be replenished as its used Less nasty for environment than no renewables Don’t provide much energy + unreliable

Question 29

What uses energy resources?

Answer 29

Transport Electricity generation Heating

Question 30

What are non-renewable energy sources?

Answer 30

They will run out They damage our environment Provide most of our energy

Question 31

Give examples of non-renewable energy stores.

Answer 31

Fossil fuels or nuclear fuels (uranium or plutonium)

Question 32

How can energy resources be used for transport?

Answer 32

Non renewable: petrol and diesel vehicles use fuel from oil, coal in steam strains Renewable: vehicles that run on biofuels

Question 33

How can energy resources be used to heating?

Answer 33

Non renewable: natural gas for hot water, coal in fires, electric heaters Renewable: geothermal heat pumps, solar water heaters, burning biofuel or using electric heaters

Question 34

What can some resources be unreliable?

Answer 34

Depend on weather

Question 35

Evaluate wind power.

Answer 35

``` Wind turbines have generators inside them which is turned by the rotation of the blades No pollution but spoil views Noisy Dependant on wind speed Initial costs are high No permanent damage to landscape ```

Question 36

Evaluate solar power.

Answer 36

``` Solar cells use sunlight Best for things which require little energy like calculators Used in remote places No pollution Very reliable Can’t increase power output High initial costs ```

Question 37

Evaluate geothermal power.

Answer 37

Possible in volcanic areas from the slow decay of radioactive elements Free reliable energy Little damage Can generate electricity or heat buildings No many suitable locations for power plants Power plants are expensive

Question 38

Evaluate hydroelectricity.

Answer 38

``` Requires flooding of dams to let uhh turbines No pollution Big impact on environment Immediate response to increased demand Reliable unless sin drought High initial costs Small scale ```

Question 39

Evaluate wave power.

Answer 39

``` Small wave powered turbines located around coast which move generators No pollution Disturbs sea bed + spoils view Hazard to boats High initial costs Large scale ```

Question 40

Evaluate tidal barrages.

Answer 40

Big dams built across estuaries with turbines inside to control output Produced by gravitational pull of sun and moon No pollution Altering habitat + spoil view + stops boats Reliable Initial costs are moderately high Only some locations

Question 41

Evaluate biofuels.

Answer 41

Renewable from plant products or animal poo that are burnt Carbon neutral Reliable - crops grow quickly Can’t respond to immediate energy demands Can be stored Very expensive Lots of space Loss of natural habitats for space Decay and burning causes CO2 and methane emissions

Question 42

Evaluate non renewables.

Answer 42

Reliable but slowly running out Cost effective Release CO2 - add to greenhouse effect + global warming Release NAO2 - causes acid rain Coal mining and oil spillages destroy landscapes Nuclear waste is dangerous but cheap

Question 43

How has electricity use changed over time?

Answer 43

20th C - huge increase | 21st C - decreasing slowly as we are making more efficient appliances and more careful with energy

Question 44

How is most of our electricity Produced?

Answer 44

Fossil fuels and nuclear power

Question 45

What have triggered the move towards renewable energy resources?

Answer 45

Damages to environment People more aware that Non renewables will run out Pressure from other countries Car companies are producing electric cars as popularity increases

Question 46

How is the use of renewables limited?

Answer 46

Money - very expensive to change Space - where to put new power plants Reliability Politics - hard to change views