Section 4 - Energy Resources and Energy Transfer

Question 1

energy stores: kinetic

Answer 1

anything moving has energy in kinetic energy store

Question 2

energy stores: thermal

Answer 2

any object - more if hotter

Question 3

energy stores: chemical

Answer 3

anything that can release energy by chem reaction (ie. foods, fuel)

Question 4

energy stores: gravitational potential

Answer 4

anything in a gravitational field (anything that can fall)

Question 5

energy stores: elastic potential

Answer 5

anything streched (like springs and rubber bands)

Question 6

energy stores: electrostatic

Answer 6

two charges that attract or repel each other

Question 7

energy stores: magnetic

Answer 7

two magnets that attract or repel each other

Question 8

energy stores: nuclei

Answer 8

atomic nuclei release energy from this store in nuclear reactions

Question 9

how can energy be transfered between stores

Answer 9

mechanically (due to a force)
electrically (due to a charge moving through p.d)
by heating ( hot to cold)
by radiation (by waves)

Question 10

principle conservation of energy

Answer 10

energy can be stored, transfered between stores, and dissipated but never created or destroyed. Total energy of a closed system has no net change.

total energy input = useful energy output + wasted energy

Question 11

useful energy

Answer 11

energy is only useful when it is transferred from one store to a useful one

some of input energy is always wasted (usually heating)

Question 12

efficiency of energy transfer

Answer 12

useful energy output
—————————— x 100
total energy output

Question 13

energy stores

Answer 13

kinetic
thermal
chemical
gravitational potential
elastic potential
electrostatic
magnetic
nuclear
(sound?)

Question 14

sankey diagram

Answer 14

thicker arrow = more energy
this then divided into smaller arrows representing energy outputs
width of arrow is proportionate to amount of Joules it represents, energy input = total output

Question 15

energy transfer by heating

Answer 15

through
radiation
convection
conduction

bigger temp difference = faster

Question 16

thermal radiation

Answer 16

consists of EM infrared waves
- all objects are continiously absorbing and emmiting infrared radiation
- an object hotter than surroundings emmits more radiation than it absorbs and vice versa
- some colours are surfaces emit and absorb radiation better than others

Question 17

conduction

Answer 17

thermal conduction is the process where vibrating particles transfer energy from their kinetic energy store to the kinetic energy stores of neighboring particles

occurs mainly in solids. when a particle vibrates its causes a ripple effect in the lattice structure creating rise in temp which means it transferes energy to surroundings

Question 18

convection of heat

Answer 18

convection occurs when the more energetic particles more from the hotter region to the cooler region and transfer energy as they do

Question 19

covection: immersion heater example

Answer 19

• particles near coils get more energy so they move faster, more distance between them means water expands and becomes less dense, causing it to rise.
• as it rises it displaces the colder water making it sink towards coils which repeats the procces
• this results in convection currents circulating energy (most efficient in roundish or squarish containers)

Question 19

reducing rate of energy transfer

Answer 19

object should be designed with a surface that is a poor emmiter
(ie. white instead of black)
use insulation to stop movement of fluid

Question 20

thermal conductivity

Answer 20

describes how well an object transferes energy by conduction. (high = quick trnasfer)

Question 21

work done

Answer 21

when a force moves an object through a distance work is done on the object and energy is transfered

move needs force needs energy (gets mechanically)

Question 22

power

Answer 22

the rate at which energy is transfered

Question 23

missing last pages and formula

Answer 23

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