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science 2 > energy: > Flashcards

energy: Flashcards

1
Q

7 main food groups:

A

dairy
carbohydrates
fat
vitamins
minerals
protein
water

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2
Q

kj and joules?

A

1 kj=1000 joules
more kj a food contains=more heat given off

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3
Q

cellular respiration:

A

process by which organisms break down sugar and turn it into energy through cells.

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4
Q

practiacal example to know how much energy food contains?

A

record starting temperature of the tube of water and when food is completely burned place it on the heat mat and record the final temperature of the water above the fire. work out the temp increase to find out which food has the highest energy. from this we learn the chemical energy stored in the the molecular bonds is released as heat and light. the heat given off can be measures in kj more heat a food contains , the more energy it contains. an example of cellular respiration.

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5
Q

joules:

A

standard unit of energy

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6
Q

how do you find out how much energy is stored in food per gram:

A

e.g cupcake has 250 kj per 100 grams
how much kj does it have per 11 grams?
250 divided by 100=2.5
2.5 times by 11 grams=27.5

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7
Q

law of conservation of energy:

A

energy before= energy after
shows energy cant be created or destroyed
only transferred and changed from one form to another

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8
Q

combustion equation:

A

process of burning something
fuel+oxygen=carbon dioxide+water

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9
Q

define fuel:

A

something you can burn and get energy from

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10
Q

types of energy:most wasted energy from their:

A

kinetic
thermal
chemical
chemical stored
gravitational potential
elastic potential
electric
sound light nuclear
thermal energy energy mostly wasted and builds up a lot in our enviroment

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11
Q

define efficiency:

A

something you pay total energy divided by useful energy times 100
washing machine-useful energy 600 total energy 700
600 divided by 700 times 100 to get it to a percent

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12
Q

thermal energy:

A

energy stored in an object

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13
Q

temperature:

A

measure of how hot or cold an object is

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14
Q

bigger/smalller object mass=

A

bigger the mass the more enrgy particles stored inside but more temperature if less mass as particles join together and in a bigger mass their more spread apart

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15
Q

when an object heated its particles..

A

gain kinetic energy=more vibrations-causing heat

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16
Q

thermal energy of a substance depends on?

A

its mass, specific heat capacity and temperature change
q=m times c times delta triangle

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17
Q

4 ways energy transfer:

A

radiation
conduction
evaporation
convection

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18
Q

radiation:

A

also known as infrared radiation
all thing emit out and give out ir
speed of light travels thru waves-electromagnetic waves
hotter-more ir emitted
doesnt need particles to work

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19
Q

eg of radiation:

A

heat from sun, microwaves, x-rays

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20
Q

conduction:

A

energy transfering thru particles, making them vibrates-an increase in heat so then the heat rising to top
metals are good thermal conductors
eg alluminium, magnesium
only solids conduct heat as fixed particles so can pass through it easily

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21
Q

eg of conduction:

A

metals are good thermal conductors

22
Q

thermal conductors and insulators:

A

conductors= materials that easily allow energy to transfer through it
insulators= materials taht don’t allow energy to transfer thru it’
water, coat, sand, vaccum, wood

23
Q

convection:

A

process which energy is transferred through heated fluids
hot air rises at top
cold air then sinks
cycle repeats
like in tea or a room with heating

24
Q

convection eg:

A

tea, air

25
Q

equalibrium:

A

balanced forces

26
Q

warm/cold air density:

A

warm air less dense as partciles move quickly causing an expansion and a distance between them rather than the density in cold air which moves slowy so closer together and more compact

27
Q

dense:

A

particles closely compacted in substances

28
Q

difference between the three energy transfers:

A

radiation-travels thru waves doesn’t need particles to occur
convection- only works with fluids, hot air rises and cold air sinks
conduction- only works with solids hot air transferred causing vibrating-rise to top

29
Q

fossil fuels and eg:

A

non renewable sources meaning they will run out eventually
coal, natural oil, gas

30
Q

why are fossil fuels so important:

A

formed millions of yrs ago from things that didnt rot so if we use it irresponsibly we wont have any left and we cant make more of it like that shabash all done

31
Q

hydrogen and define fuel:

A

hydrogen-expolsive type of fuel
fuel-something you can burn and get energy from

32
Q

how is coal made:

A

trees get trapped underground
more layers appear-causing pressure=sedimentray rocks etc.
coal produced

33
Q

how is oil and gas made?

A

plants and animals remains fall underground in ocean
remains get trapped underground for millions of years
forms oil and gas through a chemical/natural rection and collected thru pipes
eg .nordic pipe in russia

34
Q

how thermal power stations transfer energy through the energy stored in fossil energy to generate electricity:

A

water put in a furnace boiler
converted to steam and connected in wires through a generator travelling thru pylons for electricity for homes.

35
Q

power:

A

how much energy transferred per second like light

36
Q

power units:

A

watts (w)
1kw=1000 watts
lightbulb has 70w burns 70 joules every second

37
Q

EPT triangle equation:

A

energy=power times time
power=energy divivded by time
time=energy divivded by power

38
Q

equation to calculate electricty used:

A

watts times hours times 1kw/ph

39
Q

work:

A

energy transferred

40
Q

how do you find out how much work done:

A

efd trinagle

41
Q

EFD triangle equations:

A

energy-force times distance
distance=energu divivded by force
forcce=energy didvivded by distance

42
Q

simple machine:

A

something which makes a job easie by reducing the force required for it

43
Q

distance in eqautions:

A

if distance in meters convert cm to meters
divivde cm by 100 - metres
metres times 100-cm

44
Q

eg of a simple machine:

A

can opener

45
Q

lever:

A

a bar that rests and moves around a pivot like a seesaw

46
Q

eg of a lever

A

seesaw
can opener

47
Q

force multiplier:

A

when a small force applied to one end produces a big force

48
Q

more energy you put in=

A

more energy you get out

49
Q

example of levers;

A

wheel barrow
scissors
bottle opener
can opener
pilers

50
Q

conduction practical:

A

drawing pins stuck with vaseline
bunsen burner
each pin falls one by one bc metals are good thermla conductor allows energy to transfer thru it so yh.

51
Q

convection practical:

A

potassium magante VII crystals in cold water bunsen burner underneath rises to top .

science 2 (11 decks)

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