07 Energy transfers and Resources

Question 1

how mamy cm^3 in a m^3?

Answer 1

1 million

Question 2

state the equation linking density, mass and volume.

Answer 2

density=mass/v
‘p’=m/v

Question 3

what is meant by the phrase energy is conserved?

Answer 3

Energy cannot be created or destroyed, only transferred between stores

Question 4

give the acronym to remember each of the energy stores:

Answer 4

8 KG CEMENT

Question 5

give 2 properties of the Chemical store:

Answer 5

• due to the bonds between atoms
• if there are more bonds, there is more energy in the store

Question 6

give 3 properties of Kinetic store:

Answer 6

• energy in this store because something is moving
• mass and speed determine how much energy there is
• proportional to the speed ^2

Question 7

give two properties of the Gravitational store

Answer 7

• position in the gravitational field
• gravtiational field strength

Question 8

give 2 properties of the Elastic store:

Answer 8

• when soemthing is bent/stretched from initial size/ shape
• more tension there is in an object, the more energy it has in it’s elastic store

Question 9

give a property of the thermal store:

Answer 9

energy something has because of it’s temperature

Question 10

give 2 properties of electrostatic store:

Answer 10

• much to do with electric charges
• energy in kinetic store comes from energy in electrostatic store

Question 11

give 2 properties of the magnetic store:

Answer 11

• much to do with electric charges
• energy in kinetic store comes from energy in magnetic store

Question 12

give 2 properties of the nuclear store:

Answer 12

• energy stores insie the atom (not the same as chemical)
• inside the nucleus

Question 13

why is energy transferred mechanically?

Answer 13

becuase of force

Question 14

why is energy transferred electrically?

Answer 14

because it’s easy to turn into other types of energy

Question 15

what is the principle of the conservation of energy?

Answer 15

Energy within a closed system cannot be created or destroyed, only disappared and transferred between stores.

Question 16

give the equation linking efficiency, useful energy ouput, and total energy input

Answer 16

efficiency = useful energy output/ total energy input (*100%)

Question 17

if a device is more efficient, what does the mean for the amount of sueful energy?

Answer 17

the more useful energy ends up in the useful store.

Question 18

what is the most commonly wasted way of energy? [2 points]

Answer 18

heating due to friction

Question 19

how can the efficiency of a device be increased? [2 points]

Answer 19

by minimising friction (with lubricants)

Question 20

can you recycle or get dissappated energy back?

Answer 20

no.

Question 21

wat do sankey diagrams do? [2 points]

Answer 21

shows the flow of energy in a closed system
indicated what energy is useful and what is wasted

Question 22

in a sankey diagram, what is the width of each arrow proportionate to?

Answer 22

the amount of energy it indicates

Question 23

when is an experiment valid?

Answer 23

whena ll the control varibles are kept constant

Question 24

define conduction

Answer 24

the transfer of thermal energy via vibrations in solid materials

Question 25

when does conduction occur?

Answer 25

when vibrating atoms pass on their kinetic energy to the particles closest to them

Question 26

what state of matter does conduction occur in? [2 points]

Answer 26

solids the particles are fixed

Question 27

what is temperature a measurement of?

Answer 27

and object's atom's average kinetic energy

Question 28

define convection

Answer 28

the transfer of thermal energy in liquids and and gases via density changes and convection currents

Question 29

what is the simple explanation of convection? [2 points]

Answer 29

when hotter, less dense fluids rise, and colder, more dense fluid sinks.

Question 30

what state of matter does convection occur in?

Answer 30

fluids because the particles are free to flow (in an convection current)

Question 31

does hot air rise?

Answer 31

yes

Question 32

what happend to the mass of an object when it is heated?

Answer 32

stays the same

Question 33

what happend to the volume of an object when it is heated?

Answer 33

increases

Question 34

what happend to the density of an object when it is heated?

Answer 34

decreases

Question 35

define radiation

Answer 35

the transfer of thermal energy via an electromagnetic wave (infrared)

Question 36

what do hot object emit?

Answer 36

electromagnetic radiation, mostly infrared

Question 37

what state of matter does radiation occur in? [2 points]

Answer 37

vacuums because no particles required.

Question 38

where does energy always move (temperature-wise)?

Answer 38

from hot to cold

Question 39

give the qualities of black objects

Answer 39

good radiators and absorbers of heat

Question 40

give the qualities of white objects

Answer 40

poot radiators and absorbers of heat

Question 41

give the qualities of matt objects

Answer 41

good radiators and absorbers of heat

Question 42

give the qualities of shiny objects

Answer 42

poot radiators and absorbers of heat

Question 43

define evaporation

Answer 43

when the atoms on the surface of a liquid fly away

Question 44

what kind of atoms are mosy likely to fly away when evaportaion occurs?

Answer 44

atoms with the most kinetic energy

Question 45

what does evaporation do?

Answer 45

lowers the average kinetic energy