topic 2 - conservation of energy

Question 1

kinetic energy store

Answer 1

the energy of a moving object

Question 2

what does kinetic energy depend on

Answer 2

mass and speed

Question 3

kinetic energy formula

Answer 3

KE = 1/2 x mass x speed^2

Question 4

gravitational potential energy store

Answer 4

potential energy an object has due to the action of gravity on it
the energy gained by an object as it is lifted

Question 5

what does GPE depend on

Answer 5

mass, height, gravitational field strength

Question 6

gravitational potential energy formula

Answer 6

GPE = mass x gfs x change in vertical height

Question 7

thermal energy store

Answer 7

energy of an object due to its temperature

Question 8

elastic potential store

Answer 8

energy of a stretched spring or elastic band

Question 9

chemical energy store

Answer 9

energy within a chemical substance

Question 10

magnetic energy store

Answer 10

energy due to the force of attraction between two magnets

Question 11

electrostatic energy store

Answer 11

energy due to force of attraction between two electrostatic charges

Question 12

nuclear energy store

Answer 12

energy contained within an atom’s nucleus

energy released by two atomic nuclei in nuclear reactions

Question 13

conservation of energy

Answer 13

energy can be stored, transferred and dissipated but never created or destroyed

Question 14

what happens to energy in a closed system

Answer 14

in a closed system, total energy never changes

there is no NET change to the total energy

Question 15

in what 4 ways can energy be transferred

Answer 15

mechanically
electrically
by heating
by radiation

Question 16

how can energy be transferred mechanically

Answer 16

transferred by a force acting on an object

Question 17

how can energy be transferred electrically

Answer 17

transferred by a charge doing the work

Question 18

how can energy be transferred by heating

Answer 18

energy transferred from a hotter object to a cooler object

Question 19

how can energy be transferred by radiation

Answer 19

energy is transferred by waves

Question 20

energy transfers when an object is projected upwards/up a slope

Answer 20

work done against gravity

kinetic energy is transferred MECHANICALLY to gpe

Question 21

energy transfers when a moving object hits an obstacle and example

Answer 21

eg. ball hitting bat
bat transfers kinetic energy mechanically to the ball
some energy is mechanically transferred to the thermal energy stores
rest of energy is transferred as sound

Question 22

energy transfers when an object is being accelerated at a constant force and example

Answer 22

eg. rock dropping from a cliff

GPE is transferred mechanically to the kinetic energy store

Question 23

energy transfers when a vehicle is slowing down

Answer 23

kinetic energy transferred mechanically and by heating to the thermal energy store of the road and the car

Question 24

energy transfers when a kettle is boiling water

Answer 24

energy transferred electrically to the heating element

energy transferred by heating from the element to the thermal energy store of the water

Question 25

what happens when work is done mechanically

Answer 25

there is often friction the friction has to be overcome and the energy for this is transferred from kinetic energy to thermal energy energy is often dissipated by heating (wasteful)

Question 26

what tends to dissipate

Answer 26

heat, light and sound energy tend to dissipate | it is hard to gather the spreadout energy so the energy is less useful

Question 27

what happens when energy is transferred from one store to another

Answer 27

when energy is transferred from one store to another, some energy is lost

Question 28

efficiency

Answer 28

how much useful energy you get from a device compared to the energy that went into it

Question 29

efficiency formula

Answer 29

efficiency = useful energy transferred (J)/ total energy supplied (J)

Question 30

how can efficiency be improved in a mechanical system

Answer 30

to reduce unwanted energy produced in a mechanical system, you could reduce friction - you could add bearings to prevent parts from rubbing directly together - lubrication

Question 31

how can efficiency be improved in a electrical system

Answer 31

to reduce unwanted energy produced in an electrical system, you could reduce resistance - use lower resistance parts/components - lower the electrical current

Question 32

lubrication

Answer 32

lubrication can be used to reduce friction between two surfaces as they move

Question 33

what does thermal insulation do

Answer 33

thermal insulation reduces the thermal energy lost by conduction

Question 34

thermal conductivity

Answer 34

how well a material transfers energy via conduction metals/solids have high thermal conductivity gases have low thermal conductivity

Question 35

to reduce rate of cooling, what should walls be like

Answer 35

walls should be thick and have low thermal conductivity

Question 36

3 types of thermal insulation in buildings

Answer 36

loft insulation with fibreglass in double glazed windows - two sheets of glass with air gap in-between cavity walls - inner and outer walls with air in-between

Question 37

energy resources

Answer 37

large banks of energy that can be transferred into a form that can be used by society

Question 38

non-renewable energy resources (def + examples)

Answer 38

resources that will run out once day, natural resources that form underground over millions of years eg.. coal, oil, natural gas

Question 39

non-renewable energy resources features

Answer 39

typically burnt to provide energy provide most of our energy do damage to the environment

Question 40

renewable energy resources (def + examples)

Answer 40

resources which will never run out as the energy used can be 'renewed' eg.. solar, wind, hydroelectricity, biofuel, tides

Question 41

renewable energy resources features

Answer 41

don't provide as much energy reliant upon weather still damage the environment, just to a lesser extent

Question 42

what is non-renewable energy used for generally

Answer 42

non-renewable energy is used for more large-scale energy supplies due to the large energy output per kilogram of fuel

Question 43

why have renewable resources become more important

Answer 43

because of the finite lifetime of fossil fuels

Question 44

trends in energy resource use

Answer 44

during the Industrial revolution, fossil fuels were an important source of energy as it was easy to mine and provided lots of energy since the start of the 21st century, electricity use has been slowly decreasing as appliances have become more efficient and we have been more careful with energy use in our homes

Question 45

how is our energy produced

Answer 45

some of our energy is produced using fossil fuels (which we also burn to fuel cars and heat homes) and from nuclear power

Question 46

what is the aim in terms of energy resources as we move forwards

Answer 46

the aim is to begin to use more renewable resources due to pressure on the government from the public and other countries