Energy stores and transfers

Question 1

system

Answer 1

an object or a group of objects

Question 2

object in equilibrium

Answer 2

nothing changes and so nothing happens

Question 3

change to an object

Answer 3

energy is transferred

Question 4

kinetic

Answer 4

moving objects have energy

Question 5

gravitational

Answer 5

objects gain energy in their gravitational potential store as they are lifted above ground

Question 6

elastic

Answer 6

objects have energy in their elastic potential store if they are streched

Question 7

electostatic

Answer 7

objects with charge interacting with one another have energy in their electrostatic store

Question 8

magnetic

Answer 8

magnetic interacting with each other

Question 9

chemical

Answer 9

objects with energy in their chemical store can release energy

Question 10

nuclear

Answer 10

atomic nuclei release enrgy from their nuclear store during reactions

Question 11

thermal

Answer 11

all objects have energy in their thermal store, the hotter the object the more energy it contains

Question 12

energy pathways

Answer 12

mechanical
electrical
heating
radiation

Question 13

mechanical working

Answer 13

when a force acts on an object

Question 14

electrical working

Answer 14

a charge moving through a potential differencee

Question 15

heating by particles

Answer 15

energy is transferred from a hotter object to a colder one

Question 16

heating by radiation

Answer 16

energy transferred by EM waves

Question 17

principle of conservation of energy

Answer 17

energy cannot be created, or destroyed it can only be transferred from one store to another

Question 18

total amount of energy=

Answer 18

closed system
remains constant

Question 19

efficiency

Answer 19

the ratio of the useful energy output from a system to its total energy output

Question 20

system with high efficiency

Answer 20

most of the energy transferred is useful

Question 21

effieciency equation

Answer 21

efficiency= (useful energy output/total energy output) x 100%

Question 22

sankey diagrams

Answer 22

used to represent energy transfers

Question 23

left hand side sankey diagram

Answer 23

represents the energy transferred into the system

Question 24

straight arrow in sankey diagram

Answer 24

the useful energy output

Question 25

bended arrow in sankey diagrams

Answer 25

wasted energy

Question 26

total energy in equation

Answer 26

useful energy out + wasted energy

Question 27

how is energy transferred by heating and radiation

Answer 27

conduction convection radiation

Question 28

how is energy from a mug of hot coffee transferred

Answer 28

through radiation from the surface of the mug to the surroundings due to the infrared radiation being emitted from its surface

Question 29

until when do objects continue to lose heat

Answer 29

until they reach thermal equialibrium

Question 30

what are good conductors

Answer 30

metals

Question 31

what are poor conductors called

Answer 31

insulators

Question 32

what happens when a substance is heated

Answer 32

atoms start to move around and vibrate more, as they bump into each other transferring energy from atom to atom

Question 33

why are metals good at conducting heat

Answer 33

due to delocalised electrons which collide with the atoms, helping to transfer the vibrations through the material.

Question 34

convection

Answer 34

thermal energy transferred through liquids and gases

Question 35

convection current explain

Answer 35

- molecules push apart, fluid expands - makes hot fluid less dense than surroundings - hot fluid rises and cool fluid moves in to take place - hot fluid cools and sinks back down

Question 36

the more hotter the object=

Answer 36

the more infrared radiation it radiates

Question 37

what colour is the best abosrber and emitter

Answer 37

black

Question 38

what objects are the worst emitting and absorbing thermal radiation

Answer 38

shiny

Question 39

how do you reduce conduction

Answer 39

use materials with low thermal conductivity (insulators)

Question 40

reduce convection

Answer 40

currents need to be prevented from forming. - fluid that forms the current has to prevented from moving

Question 41

what reduces energy transfers from conduction and convection

Answer 41

insulation

Question 42

what does the effectiveneness of a insulator depend on

Answer 42

- thermal conductivity of material - density of material - thickness of material

Question 43

what is insulation made of

Answer 43

fibre glass

Question 44

why is glas fibre a good insulation

Answer 44

- air is trapped between the fibres which makes is a good insulator

Question 45

cavity wall insulation

Answer 45

gaps or cavities between external walls being filled with insulation.

Question 46

how is work done

Answer 46

when an object is moved over a distance by a force applied in the direction of its displacement

Question 47

energy transferred is equal to

Answer 47

work done

Question 48

equation for work done

Answer 48

W ( J)= F x d (m)

Question 49

GPE

Answer 49

the energy an object has due to its height in a gravitational field

Question 50

equation for G.P.E

Answer 50

G.P.E= mass x graviational field strength (N/kg) x height (m)

Question 51

what is the gravitational field strength of the earth?

Answer 51

10 N/kg

Question 52

why is it easier to life a mass on the moon

Answer 52

its gravitational field strength is less

Question 53

when is it harder to lift mass more than on earth

Answer 53

on bigger planets

Question 54

kinetic energy

Answer 54

the amount of energy an object has as a result of its mass and speed

Question 55

equation for kinetic energy

Answer 55

K.E= 1/2 X m x V^2 V is speed of the object

Question 56

why are pendulums an example of perfect energy trasnfers

Answer 56

all of the energy in the kinetic store is transferred mechanically to its gravitational potential store

Question 57

power

Answer 57

the rate of the energy transfer or the rate of work done

Question 58

equation for power

Answer 58

Power (W) = Word done/ time

Question 59

reneweable energy

Answer 59

an energy source that is replenished at a faster rate than the rate at which it is being used

Question 60

examples of renewable energy

Answer 60

solar energy, wind, bio fuel, hydroelectricity, geo thermal, tidal

Question 61

turbine

Answer 61

turned which turns a generator which generates electricity

Question 62

how can water be used to turn turbines

Answer 62

energy in the K store of the flowing water is transferred to the K store of the turbine and then to the K store of the generator which is trans electrically to the national grid.

Question 63

what can fossil fuels be used to turn turbines?

Answer 63

fossile fuels combusted to heat water which produced steam to turn it

Question 64

how can nuclear fuels be used to produce electricity

Answer 64

- nuclear fuels are used to heat water to produce steam to turn it - nuclear store -> thermal store of water -> kinetic store of turbine -> kinetic store of generator

Question 65

advantages of reneweable energy

Answer 65

- reliable as it won't run out - sometimes not reliable such as wind energy

Question 66

pros and cons of fossiul fuels

Answer 66

- reliable and can produce a large amount of energy - produces GHG and pollution

Question 67

pros and cons of nuclear energy

Answer 67

- reliable and doesn't pollute - produces radioactive waste that takes thousands of years to decay

Question 68

pros and cons of hydroelectricity energy

Answer 68

- reliable and can produce large amounts of energy - flooding large areas, destroy wildlife

Question 69

pros and cons of wind energy

Answer 69

- no GHG, no pollution - not reliable, turbines are ugly and noisy