Conservation of Energy

Question 1

What are the 6 main types of energy?

Answer 1

• Chemical - food, batteries and fuel
• Kinetic - moving
• Thermal - hot objects
• Strain/Elastic - squashed or twisted materials
• Gravitational potential energy - objects in high positions
• Atomic/nuclear energy - energy stored inside atoms

Question 2

Can energy be transferred?

Answer 2

Yes, for example kinetic energy stored in a bullet is transferred to a person by forces; some of this energy is stored in the moving fragments of the person, and some will heat up the person

Question 3

What is the law of conservation of energy?

Answer 3

Where energy cannot be created or destroyed in a system; it can only be transferred from one store to another - the total energy transferred by a system is the same energy put into the system

Question 4

What are the units for measuring energy?

Answer 4

Joules (j)

Question 5

What type of diagram shows the amount of energy transferred?

Answer 5

Sankey diagram - the width of the arrows represent the amount of energy in joules

Question 6

What does it mean when energy is dissipated?

Answer 6

It spreads out

Question 7

How can friction between moving parts be reduced?

Answer 7

Lubrication - oil/other liquids (even sometimes gases) can be used as lubricants

Question 8

What is efficiency?

Answer 8

The way of describing how good a machine is at transferring energy into useful forms

Question 9

How do you calculate efficiency?

Answer 9

Useful energy transferred by the device/Total energy supplied to the device

Question 10

What happens in conduction?

Answer 10

Vibrations are passed on between particles in a solid

Question 11

What happens in convection?

Answer 11

Part of a fluid that is warmer than the rest rises and sets up a convection current

Question 12

What is radiation the only way of?

Answer 12

In which energy can be transferred through a vacuum

Question 13

What does it mean if an object has low thermal conductivity?

Answer 13

Energy is not transferred through them very easily by heating

Question 14

What happens when air is trapped?

Answer 14

It can’t form convection currents and so does not transfer much energy

Question 15

What does the rate of energy being transferred through a material depend on?

Answer 15

Its thickness, its thermal conductivity and also on the temperature difference across it

Question 16

How is the rate of energy transfer reduced?

Answer 16

Increasing the thickness, decreasing thermal conductivity and decreasing temperature difference

Question 17

What is gravitational potential energy?

Answer 17

Energy that is stored because of an object’s position in a gravitational field

Question 18

What does the GPE of an object depend on?

Answer 18

The mass of the object, the strength of gravity and how far the object is moved upwards

Question 19

How do you calculate the change in GPE?

Answer 19

CHANGE IN GPE (J) = MASS (KG) x GRAVITATIONAL FIELD STRENGTH X CHANGE IN VERTICAL HEIGHT (M)

Question 20

What does the amount of kinetic energy stored in a moving object depend on?

Answer 20

Its mass and its speed

Question 21

How can kinetic energy be calculated?

Answer 21

KINETIC ENERGY (J) = 1/2 X MASS(KG) X SPEED SQUARED (M/S SQUARED)`

Question 22

Why is nuclear fuel useful for spacecraft?

Answer 22

Because nuclear fuels store a lot of energy in a small piece of material, and mass of the fuel is important for spacecrafts

Question 23

Name examples of non-renewable energy fossil fuels

Answer 23

Coal, oil and natural gas

Question 24

What does non-renewable mean?

Answer 24

They will run out one day

Question 25

What is good about non-renewable resources?

Answer 25

They store a lot of energy and are easy to store and use in engines like ships, aeroplanes and vehicles

Question 26

What is bad about burning fossil fuels?

Answer 26

They contribute to climate change (pollution problems)

Question 27

What are the good and bad parts of nuclear power stations?

Answer 27

Good - they don't emit any carbon dioxide or other gases Bad - the waste they produce is radioactive and some of it will stay radioactive for years; it is very expensive to dispose of safely and very expensive to decommission a nuclear power at the end of its life. Also, even though accidents there are rare, if they do happen it can have serious consequences despite being designed to avoid radioactive leaks

Question 28

What does decommission mean?

Answer 28

To dismantle safely

Question 29

What are renewable resources?

Answer 29

Energy resources such as solar or wind energy that will not run out (most don't emit polluting gases)

Question 30

How does solar energy work?

Answer 30

Solar cells convert solar energy into electrical energy which are caught by solar panels to provide renewable energy

Question 31

How is hydroelectricity generated?

Answer 31

By falling water in places where water can be trapped in high reservoirs, which is available at any time

Question 32

When can wind turbines be used to generate electricity?

Answer 32

As long as the wind speed is not too slow or too fast

Question 33

When can tidal power generate electricity?

Answer 33

When turbines in a huge dam across a river turn as the tides flow in and out

Question 34

Why is tidal power not available at all times in many places in the UK?

Answer 34

Many places are not suitable for barrages and they may affect birds and other wildlife that live/feed on tidal mudflats

Question 35

What are bio-fuels made from?

Answer 35

Animals wastes, parts of plants that aren't used in food, waste wood, or some crops that are specifically grown to be made into bio-fuels

Question 36

Why are bio-fuels called carbon neutral?

Answer 36

Because when they burn, they release the same amount of CO2 as they took from the atmosphere when the plants grew (don't generate more than they took in)

Question 37

Why could it be argued that bio-fuels aren't really carbon neutral?

Answer 37

Energy is also needed to grow and harvest the crops and turn them into fuel