Topic 3 - Conservation Of Energy

Question 1

efficiency

Answer 1

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

Question 2

chemical energy

Answer 2

energy stored in food, fuel and batteries

Question 3

kinetic energy

Answer 3

energy stored in moving objects

Question 4

thermal energy

Answer 4

energy stored in hot objects

Question 5

elastic potential energy

Answer 5

energy stored in stretched, squashed or twisted materials

Question 6

gravitational potential energy

Answer 6

energy stored in objects in high position

Question 7

atomic energy/nuclear energy

Answer 7

energy stored inside atoms

Question 8

law of conservation of energy

Answer 8

energy cannot be created or destroyed; can only be transferred from one store to another
-> this means that the total energy transferred by system is the same as the energy put into the system

Question 9

sankey diagram

Answer 9

the amount of energy that is transferred (it shows the useful and wasted energy)
-> the width of the arrows represents the amount of energy in joules

Question 10

how is the efficiency of a machine described

Answer 10

between 0-1 - the higher the number the more efficient the machine

Question 11

efficiency equation

Answer 11

efficiency = useful energy transferred by the device
total energy supplied to the device

Question 12

what is wasteful energy

Answer 12

energy that is not used in the process and is transferred into the surroundings (e.g. when a lights turned on, heat gets dissipated into the surroundings; heat is wasted energy

Question 13

electrical energy

Answer 13

energy stored in electricity

Question 14

kinetic energy symbol equation

Answer 14

kinetic energy = 1/2 x m x v2

Question 15

what does insulation do

Answer 15

slows down the rate at which energy is transferred out of a house by heating

Question 16

conduction

Answer 16

vibrations are passed on between particles in a solid, easy energy transfer
—> metals are good thermal conductors and materials such as wood are poor thermal conductors (good thermal insulators)

Question 17

convection

Answer 17

part of a fluid (liquid or gas) that is warmer than the rest rises and sets up a convection current

Question 18

radiation

Answer 18

the only way in which energy can be transferred through a vacuum

Question 19

infrared radiation

Answer 19

can also pass through gases and some solid materials
—> absorbed and emitted easily by dull, dark surfaces and emitted poorly by light, shiny surfaces

Question 20

what effects the rate at which energy is transferred through material by heating

Answer 20

• it’s thickness
• thermal conductivity
• temperature difference across it

Question 21

potential energy

Answer 21

possible energy stored in an object

Question 22

gravitational potential energy

Answer 22

the Nagy store in a object due to gravity (it’s position in a gravitational field)

Question 23

gravitational potential energy equation

Answer 23

gravitational potential energy (J) = mass (kg) x height (m) x gravitational field strength (N/kg)

Question 24

kinetic energy word equation

Answer 24

kinetic energy = 1/2 x mass x (speed)2
(J) (kg) (m/s)2

Question 25

when a object moves closer to the surface what’s the energy change?

Answer 25

GPE turns into KE

Question 26

non-renewable energy resources

Answer 26

resources that will run out one day

Question 27

renewable energy resources

Answer 27

resources that will not run out (natural)

Question 28

name renewable energy sources

Answer 28

• solar energy (takes sun rays and converts it into energy)
• wind energy (wind turbines use wind to drive turbines and generate electricity)
• hydro energy (convert the gravitational potential or kinetic energy to produce power)
• tidal energy (produced by converting energy from the natural rise and fall of tides into useful forms of power, mainly electricity)
• bio fuel (made from animal wastes or from plants and are burned to create energy)
• geothermal energy (heat energy from earth)

Question 29

name non-renewable energy sources

Answer 29

• fossil fuels (fossil fuels are burned to produce energy)
• coal energy (primarily used as fuel to generate electric power)

Question 30

dissipated

Answer 30

Spread out

Question 31

Why are fuels made from oil used in vehicles?

Answer 31

• they store a lot of energy
• they’re easy to store and use in engines

Question 32

what are two advantages of using natural gas instead of coal to generate electricity?

Answer 32

• natural gases cause less pollution than burning coal
• Natural gas power stations also admit less common dioxide than other fossil fuel power stations producing the same amount of electricity

Question 33

advantages of nuclear power over fossil fuel power stations

Answer 33

• Nuclear power stations do not admit any carbon dioxide or other gases

Question 34

disadvantages of nuclear power over fossil fuelled power stations

Answer 34

• The waste nuclear power stations produce is radioactive and some of it will stay radioactive for millions of years
• This radioactive waste is expensive to dispose of safely
• Nuclear power stations are expensive to decommission (dismantle safely) at the end of its life —> more expensive

Question 35

How can a student calculate the demand energy transferred to the surroundings?

Answer 35

Input - output