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Science > P7 > Flashcards

P7 Flashcards

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1
Q

what is work

A

the amount of energy transferred

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2
Q

what is the equation for work

A

work = force * distance

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3
Q

what is the unit for work

A

joules

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4
Q

what is the unit for force

A

newtons

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5
Q

what is the unit for distance

A

metres

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6
Q

what is power

A

the rate at which energy is transferred/supplied

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7
Q

what is the equation for power

A

power = energy/time

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8
Q

what is the unit for power

A

watts

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9
Q

what is the unit for energy

A

joules

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10
Q

what is the acronym for energy stores

A

green sick

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11
Q

what are the energy stores

A
  • gravitational potential
  • radiant (light)
  • electrical
  • elastic potential (strain)
  • nuclear
  • sound
  • internal (thermal)
  • chemical
  • kinetic
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12
Q

how is energy transferred between stores

A
  • forces (mechanical work done)
  • electrical currents (electrical work done)
  • heating
  • electromagnetic/sound/other waves
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13
Q

what is the principle of conservation of energy

A

energy can neither be created nor destroyed, only be converted from one form to another

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14
Q

what is the equation for kinetic energy

A

KE = 1/2* mv^2

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15
Q

what is the equation for gravitational potential energy

A

gpe= mgh

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16
Q

how is efficiency calculated form energy and power

A

(useful energy output/energy input) *100%

(useful power output/power input) *100%

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17
Q

what is the spring constant

A

force per unit extension

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18
Q

what is hooke’s law

A

extension of elastic object is directly proportional to load force being applied

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19
Q

what is equation for spring constant

A

k = F/x

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20
Q

what is the limit of proportionality

A

the “limit” force that can be applied before F & x stop being directly proportional

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21
Q

how to work out spring constant on graph

A

gradient

22
Q

examples of renewable energy sources

A
  • wind
  • geothermal
  • water (wave, hydroelectric, tidal)
  • biomass/biofuel
  • heat/light from sun
23
Q

examples of non-renewable energy sources

A
  • fossil fuels
  • nuclear fission
24
Q

how is energy obtained from chemical energy stored in fuel

A
  • set on fire
  • which boils water to spin turbine
  • or used in combustion engine
25
Q

how is energy obtained from waves

A
  • buoy bobs up and down on waves
  • turns turbines
26
Q

how is energy obtained from tides

A
  • flow of water turns generator
27
Q

how is energy obtained from hydroelectric dams

A
  • water flows downhill (gpe–>ke)
  • spins turbine
28
Q

how is energy obtained from geothermal resources

A
  • heat from earth evaporates water
  • spins turbine
29
Q

how is energy obtained from nuclear fission

A
  • nuclear fuel rods get hot
  • heat gas (often water) to spin turbine
30
Q

how is energy obtained from heat and light from sun

A
  • cells: sunlight creates voltage across semiconductor material
  • panels: sunshine heats water in tank
31
Q

how is energy obtained from wind

A
  • as wind passes, spins turbine
32
Q

what are the steps in a power generator

A
  • boiler: chemical to internal
  • turbine: internal to kinetic
  • generator: kinetic to electrical
  • transformer: change voltage
33
Q

what are advantages of fossil fuels

A
  • easy to use (burn it)
  • can be transported to where needed
  • cheap
34
Q

disadvantages of fossil fuels

A
  • burning releases greenhouse gases: global warming
  • harm environment (oil spills, soot from coal)
35
Q

advantages of wave energy

A
  • plentiful space out at sea
  • renewable
  • plentiful in windy places
36
Q

disadvantages of wave energy

A
  • seawater corrodes machinery, maintenance challenging
  • far away from cities/industries
37
Q

advantages of tidal energy

A
  • reliable: happens every day as earth turns
  • renewable
  • no harmful gases produced
38
Q

disadvantages of tidal energy

A
  • require suitable location
  • expensive to build
39
Q

advantages of hydroelectric dams

A
  • renewable
  • very short start-up/response time
40
Q

disadvantages of hydroelectric dams

A
  • location dependent (hilly, wet places, not flat)
  • can be expensive to initially construct)
41
Q

advantages of geothermal energy

A

free and renewable
- no greenhouse gases

42
Q

disadvantages of geothermal energy

A
  • dependent on location
  • hot areas more accessible in tectonically active places
  • initial cost to build infrastructure
43
Q

advantages of nuclear fission

A
  • high energy density
  • no greenhouse gases produce
44
Q

disadvantages of nuclear fission

A
  • radioactive waste
  • expensive to build
45
Q

advantages of heat and light energy from sun

A
  • sunlight free and reliable in some places
  • easy to install
46
Q

disadvantages of heat and light energy from sun

A
  • require large surface area to provide reasonable amount of power
47
Q

advantages of wind energy

A
  • renewable
  • works well anywhere with wind
48
Q

disadvantages of wind energy

A
  • dependent on wind
  • moderately expensive to build
49
Q

what is the source of tidal energy

A

moon

50
Q

which energy resources have the sun as the source

A

all except tidal, geothermal, nuclear

51
Q

how is energy released in the sun

A

nuclear fusion

Science (22 decks)

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