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Question 1

What is a system?

Answer 1

A system is an object or a group of objects

Question 2

What is a closed system?

Answer 2

A system where neither matter nor energy can enter or leave. The net change in the total energy of a closed system is always zero

Question 3

What are the 8 energy stores?

Answer 3

1. kinetic energy store
2. gravitational potential energy store
3. elastic potential energy store
4. chemical energy store
5. thermal(internal) energy store
6. nuclear energy store
7. electrostatic energy store
8. magnetic energy store

Question 4

What are the four ways energy can be transferred?

Answer 4

1. mechanically
2. by heat
3. by radiation
4. electrically

Question 5

State the conservation of energy

Answer 5

Energy cannot be created or destroyed. It can only be transferred usefully, stored or dissipated

Question 6

Explain what happens as water boils in an electric kettle

Answer 6

energy is transferred to the water by heating, into the water’s thermal energy store and this causes the temperature of the water to rise

Question 7

What is work done?

Answer 7

the amount of energy transferred

Question 8

Explain what happens when an object (e.g. a ball) is projected upwards

Answer 8

• the initial force exerted by a person to throw a ball does work.
• Energy is transferred from the chemical store of the arm to the kinetic energy store of the ball and arm and the gravitational potential energy store of the ball

Question 9

Explain what happens as a car slows down

Answer 9

• the frictional forces cause a transfer of energy
• energy is transferred from the wheels’ kinetic energy store to the thermal energy store of the surroundings

Question 10

What is the equation to calculate kinetic energy?

Answer 10

kinetic energy = 0.5 × mass × (speed)^2

Ek= joules
mass= kg
speed= m/s

Question 11

What is an elastic potential store?

Answer 11

any object that is stretched, twisted or compressed

Question 12

How can you calculate the elastic potential energy in a stretched spring?

Answer 12

elastic potential energy = 0.5 × spring constant × (extension)^2

Ee= joules
Spring constant(k)= N/m
extenstion= m

Question 13

equation for gravitational potential energy

Answer 13

Gravitational potential energy= mass x gravity x (change in) height

Ep= joules
mass=kg
gravity= N/Kg e.g. Earth=9.8
height= metres

Question 14

equation to calculate the amount of energy stored in/ released from a system as its temperature changes?

Answer 14

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

Δ E = m c Δ θ

mass= kg,
shc(c)= J/kg°C

Question 15

What is internal energy?

Answer 15

The energy stored inside a system by particles that make up the system. Internal energy is the total kinetic energy and potential energy of all particles in the system

Question 16

What is specific heat capacity?

Answer 16

The amount of energy it takes to raise the temperature of 1kg of a substance by 1 degree Celsius.

Question 17

What effect does thermal conductivity have on the rate of energy transfer?

Answer 17

The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material

Question 18

Explain how a convection current works

Answer 18

A convection current is formed by a constant transfer of energy by heating to the substance. As the air is heated it becomes less dense so it rises whilst the cold air sinks. Once the heated air is away from the heater it becomes colder and then sinks allowing the hot air to rise. This then continues in a cycle

Question 19

Why are runners given foil blankets?

Answer 19

The heat would reflect light (infrared radiation) off the surface and back to heat the runners

Question 20

How can you make your walls in your home reduce the amount of energy wasted?

Answer 20

• having thicker walls
• having walls made with a material with a LOW thermal conductivity (less energy transfer via conduction)

Question 21

What else may be put in place in homes to reduce energy transfer?

Answer 21

• loft insulation
• double glazed windows
• cavity wall insulation
• fit carpets

Question 22

What are the roles of lubricants?

Answer 22

Lubricants reduce the friction between the surfaces of objects that are rubbing together

Question 23

Define power

Answer 23

power is the rate at which energy is transferred or the rate at which work is done

Question 24

What is the equation linking power, energy transferred(or work done) & time?

Answer 24

P= E/t, power=energy transferred/time

P=W/t
power=work done/ time

Question 25

True or False: An energy transfer of 1 joule per second is equal to a power of 1 watt

Answer 25

True

Question 26

Define efficiency

Answer 26

Efficiency is the proportion of input energy transferred which is usefully transferred

Question 27

What are the two equations for efficiency?

Answer 27

1. efficiency=useful output energy transfer/ total input energy transfer 2. efficiency= useful power output/ total power input

Question 28

How can the efficiency of a system be increased?

Answer 28

1. reducing waste output-by lubrication, thermal insulation 2. recycling waste output- recycling thermal waste energy as input energy

Question 29

How can the efficiency of a mechanical machine with moving parts be improved?

Answer 29

Lubricate any moving parts to reduce the friction and therefore energy loss due to heating

Question 30

How can the efficiency of a radiator be improved?

Answer 30

Installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the walls

Question 31

What is a non-renewable energy resource?

Answer 31

A non-renewable energy resource is one that has a limited supply & it will run out at some stage because they are used faster than they can be replaced

Question 32

What are the main energy resources available for use on Earth?

Answer 32

- fossil fuels(coal, oil, gas) - biofuels(plant products, animal dung) - nuclear fuel(uranium, plutonium) - wind - solar - geothermal - hydro-electricty - tides - waves

Question 33

What is a renewable energy source? give examples

Answer 33

A renewable energy resource is one that can be replenished as it is used 1. solar 2. wind 3. biofuels 4. geothermal 5. hydro-electricity 6. waves 7. tidal barrages

Question 34

Give examples of non-renewable energy resources

Answer 34

- fossil fuels - nuclear power

Question 35

Give 2 advantages and 2 disadvantages of fossil fuels

Answer 35

**Advantages** - fossil fuels are easy to obtain - fossil fuels provide a cost effective energy resource **Disadvantages** - The carbon dioxide produced adds to the greenhouse effect - burning coal releases sulfur dioxide which causes acid rain

Question 36

Give 2 advantages and 2 disadvantages of nuclear power

Answer 36

**Advantages** - less fuel offers more energy - no carbon dioxide is produced **Disadvantages** - the waste is hard to dispose of - gives off harmful waste products

Question 37

Give 2 advantages and 2 disadvantages of biofuels

Answer 37

**Advantages** - fairly reliable as plants take a short time to grow - biodiesel has a higher flash point, which means it is safer as it does not ignite easily - carbon neutral: it uses the same amount as any carbon it produces so there’s no overall release of carbon **Disadvantages** - high costs are needed to refine biofuels - large amounts of water and space are needed to grow the crops

Question 38

Give 2 advantages and 2 disadvantages of wind power

Answer 38

**Advantages** - produces no pollution - no fuel costs - does not cause any permanent damage to the landscape **Disadvantages** - no power when the wind stops - can be very noisy - can not increase the supply when there is a higher demand as it relies on the wind -visual pollution

Question 39

Give 2 advantages and 2 disadvantages of solar cells

Answer 39

**Advantages** - produces no pollution - energy is free and the running costs are almost nil - perfect for providing energy for devices that do not need large amounts of energy **Disadvantages** - no energy at night when there is no sun (can only be generating during daytime) - generates energy on a relatively small scale

Question 40

Give 2 advantages and 2 disadvantages of geothermal power

Answer 40

**Advantages** - free energy - reliable - very little impact on the environment **Disadvantages** - there are not many suitable location for the power stations - building costs for the power stations are very high

Question 41

Give 2 advantages and 2 disadvantages of hydro-electric power

Answer 41

**Advantages** - no pollution - can provide an instant response to an increased demand of energy **Disadvantages** - environmental impacts e.g. rotting vegetables - reservoirs look unpleasant when they dry up

Question 42

Give 2 advantages and 2 disadvantages of wave power

Answer 42

**Advantages** - no pollution - no fuel costs - can be useful on small island **Disadvantages** - can be a hazard to boats - disturbs the seabed and the habitats of marine animals

Question 43

Give 2 advantages and 2 disadvantages of tidal barrages

Answer 43

**Advantages** - no pollution - no fuel costs - has the potential for generating large amount of energy **Disadvantages** - spoils the view and alters the habitat - the height of the tide is a variable - prevents free access by boats