Energy

Question 1

Name the 8 stores of Energy

Answer 1

Gravitational Potential

Elastic potential

Electrostatic

Kinetic

Sound

Nuclear

Chemical

Heat (Thermal)

Question 2

Name the 5 ways energy can be transferred

Answer 2

Mechanically (moving due to force)

Electrically (a charge moving through pd)

By heating (energy from a warmer to a colder object)

Radiation (eg energy from the sun)

Light or sound waves

Question 3

The conservation of energy principle

Answer 3

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

Question 4

What is the difference between an open and closed system

Answer 4

In an open system energy can be transferred with the world outside the system so it can lose or gain energy.

Closed systems do not. Their energy is only transferred within the system so the overall net change of energy is always 0

Question 5

What is the equation for Kinetic energy (with units)

Answer 5

KE = ½mv²

Kinetic energy = 0.5 x mass × speed²

KE = Joules
Mass = Kilograms
Speed = metres per second

Question 6

With the same amount of energy but different masses, out of two objects, which would have more kinetic energy

Answer 6

The object with a larger mass

Question 7

What is the difference between weight and mass

Answer 7

Mass is how much we weigh, whereas weight is our mass multiplied by the rate of gravitaional pull

Question 8

What is the formula for Gravitational Potential Energy

Answer 8

Ep = M G H

gpe= mass × gravitational field strength × height

Ep = Joules
Mass = Kilograms
Gravitational field strength = Newtons per kilogram
Height = metres

Question 9

What happens to the GP(E) when an object is falling

Answer 9

It is transfered in Kinetic Energy

Question 10

Name elements with low thermal conductivity

Answer 10

Plastics and Fluids

Question 11

Name a group of elements with high thermal conductivity

Answer 11

Metal

Question 12

Explain convection

Answer 12

Takes place in fluids
Move around much faster when provided with energy
Warm air will rise (as they’re less dense)
Then cool and fall
Then rise again in a convection current

Question 13

Radiation

Answer 13

Energy can be transfered within a vacuum (without other particles)

Energy is carried by Infared waves

Question 14

What ways are there to reduce heat loss in the home (4)

Answer 14

Sealing the house closed (foam seals and closing curtains)

Thick walls with low conductivity material to prevent conduction

Cavity walls (two layers of brick with a gap in between) but instead of a gap there should be insulated material with tiny air bubbles to prevent conduction and convection simultaeneously

Double glazed windows. Two layers of window with a gap in between

Question 15

What are the 2 definitions of Power

Answer 15

Power is the rate at which energy is transferred

P= E/T
Power = Energy ÷ Time

Power= Watts
Energy= Joules
Time = Seconds

————————–OR————————-

Power is the rate at which work is done

P = W / T
Power = Work ÷ Time

Power = Watts
Work done = Joules
Time = Seconds

Question 16

What is the equation for efficiency

Answer 16

Efficiency = useful output energy / total input energy

As a percentage (multiple by 100)

Question 17

No device is 100% effecient, with 1 exception. What is the exception?

Answer 17

Electric heaters

All the energy is transferred usefully yk thermal energy stores

Question 18

How can the efficiency of an energy transfer be improved?

Answer 18

Lubrication and Insulation to stop thermal energy being lost

Question 19

What is Specific Heat Capacity

Answer 19

The amount of energy needed to raise the temperature of 1kg of la substance by 1°C

Question 20

What happens with materials that require a large amount of energy to raise their temperature

Answer 20

They also release alot of energy when they cool down

Question 21

What is a lubricant

Answer 21

Usually a liquid, like oil, that is put between 2 objects to reduce the friction and hence build up of thermal energy between them

Question 22

Name the 4 natural non-renewable energy resources

Answer 22

Coal
Oil
Gas
Nuclear fuels

Question 23

Name the 7 renewable energy resources

Answer 23

Wind
Tides
The sun
Bio-fuel
Water waves
Hydroelectricity
Geothermal

Question 24

How is energy used for Transport? (Vehicles and trains)

Answer 24

Petrol and diesel used for vehicles

Some steam trains boil water to produce steam (Coal)

Question 25

How is non-renewable energy (natural gas, coal and oil) used for heating

Answer 25

Natural gas- burned to heat water which is pumped into radiators at home Oil- burning oil from a tank to produce heat Coal- burnt in fireplaces

Question 26

How is renewable energy used for heating? (Solar and geothermal)

Answer 26

Geothermal- a geothermal heat pump can be used to generate heat in buildings Solar power- solar water heaters use electromagnetic radiation from the sun to heat water which is pumped into the building's radiators

Question 27

Where are wind turbines to be placed and why?

Answer 27

They should be near coasts or moors do they can be exposed to alot of wind to maximise the amount of energy generated.

Question 28

Explain how wind turbines work and evaluate their use. (5?)

Answer 28

The turbine blades spin in the wind and directly drive a generator, they are attached to, to generate electricity They produce no pollution and are renewable but some argue they ruin the view. Around 1500 turbines would be needed to replace a single power station. They can be noisy. There will be issues if there is no wind or too much wind. The initial costs are quite high, but there are no fuel costs

Question 29

Explain how solar power works and evaluate their use. (3)

Answer 29

Electric current is generated directly from the sun's radiation. No pollution and not alot of energy required to manufacture. Initial costs are high but then the energy is free with no running costs.

Question 30

Explain how geothermal power works and evaluate their use. (3)

Answer 30

Energy from the thermal energy stores of hot rocks underground are used to generate electricity. (Source- slow decay of radioactive elements in the earth) The steam and hot water rise to the surface to drive a turbine, which turns a generator which conducts electricity. Free energy, very little impact on the environment. Costs alot compared to the amount of energy collected

Question 31

Explain how hrdyroelectricity is generated and evaluate it's use. (5)

Answer 31

*Flooding of a valley by building a dam is required* Water is held back behind a dam. When it is released it passes through turbines which turn a generator and generates electricity No pollution. Effect on the environment- flooding leads to rotting vegetation which releases methane and CO² (greenhouse gases) Can provide an immediate response to greater demand. Always work, unless drought. Initial costs are high, but no fuel costs Used on a small scale in remote areas

Question 32

Explain how wave power works and evaluate it's use.

Answer 32

Lots of small wave-powered turbines are to be located around the coast. The up and down motion of the waves as they come in will drive a generator. No pollution produced. Disturbing the habitats of marine animals. Unreliable as waves can die out with no wind. Initial costs are high, but no fuel costs and low running costs. Not alot of energy produced, useful for only small islands

Question 33

Explain how tidal barrages work and evaluate their use.

Answer 33

Big dams are built across river estuaries with turbines in them. As the tides come in and fill the estuary up to several metres, the water can be allowed through the turbines at a controlled speed to generate electricity. No pollution. Restricts access by boat and alters the habitat of the wildlife. Tides are quite reliable, but can be varied in height. Initial costs are moderately high, but no fuel costs and low running costs

Question 34

Explain how bio-fuels work and evaluate their use.

Answer 34

Biofuels are renewable energy resources that are created from either plant products or animal faeces. They can be any state of matter and can be burned to produce electricity or run cars in the same way as fossil fuels. Reliable due to the availability of crops all year round but cannot respond to immediate energy demands. Biofuels made from plants are carbon nuetral, as when they are burned, they release CO² but while they are growing, the absorb CO² Methane produced from the animals Species losing their natural habitats as alot of land can be cleared to make room to grow bio-fuels

Question 35

Explain how power stations work in terms of fossil fuels and evaluate their use.

Answer 35

The fuel is fed into the boiler and the steam produced is then sent to the turbine, which is linked to a generator. Electricity is generated and transferred to the national grid. Cost effective, large amounts of energy, readily available for demands. Setup is very expensive but lower fuel and running costs. Alot of fuels are available at the moment, but are quickly running out. Coal --> Oil --> Gas Alot of CO² emitted Burning Coal and Oil produce sulfur dioxide resulting in acid rain. (Reduced by taking sulfur out of fuel before burning) Coal mining messes up the landscape

Question 36

Explain how nuclear power stations work and evaluate their use.

Answer 36

Similar to fossil fuel power station, except the fuel isn't burnt. Nuclear fission of nuclear fuels releases energy to heat water into steam which drives turbines. Stations take longest time to start up. No harmful gases are chemicals produced, small amount of pollution. Reliable, enough fuel to meet current demand. Nuclear waste is very dangerous to duspose of as it stays radioactive. Nuclear fuel is cheap but the cosy of the power station is very high. Risk of equipment failure, like Chernobyl