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yr 2 science eye > chapter 9 > Flashcards

chapter 9 Flashcards

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1
Q

types of forces

A
  • contact force
  • non-contact force
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2
Q

contact forces:

A
  • friction
  • elastic force
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3
Q

friction definition

A

force that opposes motion between 2 surfaces in contact

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4
Q

friction example

A
  • climbers use chalk, which absorbs moisture, increasing friction and improving their grip.
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5
Q

elastic force

A

force that allows a stretched/compressed object to return to its original shape

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6
Q

elastic force examples

A

climbing ropes: can stretch and exert elastic force. when a climber falls, the elastic force exerted increases, reducing impact

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7
Q

non-contact forces:

A
  • gravitational forces
  • magnetic force
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8
Q

gravitational force

A

force that attracts 2 objects towards each other

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9
Q

weight definition

A

measure of gravitational force acting on an object

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10
Q

magnetic force

A

force exerted between a magnet and another magnetic material/magnet

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11
Q

attraction and repulsion

A
  • like poles repel
  • unlike poles attract
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12
Q

magnetic force example

A

maglev train
- due to repulsion, the train floats slightly above the track
- reduces friction, allowing the train to travel faster

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13
Q

SI unite of weight

A

N, Newton

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14
Q

mass definition

A

amount of matter in an object

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15
Q

SI unit of mass

A

kg, kilogram

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16
Q

how to measure forces

A

spring balance

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17
Q

pulling a block using a spring balance, smooth VS rough surface

A

smooth: less force needed
rough: more force needed

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18
Q

weight in different location

A
  • changes with location
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19
Q

mass in different location

A
  • remains the same regardless of location
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20
Q

changes in state of rest/motion of an object

A
  • move a stationary object
  • stop a moving object
  • change the speed of object
  • change in direction in which object moves
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21
Q

pivot definition

A

the point around which the object can rotate or turn

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22
Q

turning effect example

A

removing lid of a tin can

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23
Q

changes in size/shape of object

A
  • blowing up balloon
  • change of shape of sponge
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24
Q

pressure

A

an effect of force acting on an object

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25
Q

pressure factors

A
  • amount of force
  • contact area
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26
Q

pressure formula

A

force/area = pressure
n/m2, Pa (pascal)

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27
Q

pressure example (needle)

A
  • needle has to be very sharp
  • surface area with skin is small
  • high pressure is applied -> pierce skin easily
28
Q

pressure in liquids

A
  • the deeper we are underwater, the high the pressure
29
Q

application of pressure in liquid: dam

A

base of dam is very thick because water pressure is higher at the base of the dam compared to the top
- when water levels rise, pressure at the bottom will increase -> thicker walls

30
Q

atmospheric pressure relationship (height)

A

the higher we are, the less atmospheric pressure

31
Q

drinking straw

A
  • when you suck on a straw, air is removed from inside of it
  • air pressure in straw decreases, becoming lower than the surrounding atmospheric pressure
  • high atmospheric pressure pushes liquid up the straw and into the mouth
32
Q

suction cup

A
  • when the suction cup is pressed down, air is pushed out from under the cup
  • air pressure between the surface and suction cup decreases (lower than atmospheric pressure)
  • higher atmospheric pressure holds suction cup in place
33
Q

work done

A
  • when a force is applied on an object and causes it to move the same direction as the force
34
Q

work down unit

A

joules (J)

35
Q

work done conditions

A
  • force applied on object
  • object moves in same direction as force
36
Q

lifting a box from the floor (work done?)

A

yes

37
Q

carrying a box in a fixed position (work done?)

A

no

38
Q

box is carried and moved forward (work done?)

A

no

39
Q

check page 24 textbook

A
40
Q

sources of energy:

A
  • fossil fuels
  • bio-fuels
  • nuclear energy
  • geothermal energy
  • wind energy
  • solar energy
  • hydroelectric energy
41
Q

fossil fuel:

A
  • non-renewable
  • formed from remains of dead animals/plants
42
Q

fossil fuels equation

A

chemical potential energy
-> heat energy
-> kinetic energy
-> electrical energy

43
Q

impact of fossil fuels on the environment

A
  • releases air pollutants
  • contribute to global warming
44
Q

solar energy

A

solar panels trapping sunlight to convert to electrical energy

45
Q

solar energy equation

A

light energy (the sun)
-> electrical energy (solar cell)

46
Q

impact of solar panels

A
  • envrionmentally friendly
  • disposal/production may generate toxic waste
47
Q

hydroelectric energy

A

electrical energy generated by turbines when moving water powers them
- stores water behind the dam
- water released powers turbines to generate electrical energy

48
Q

hydroelectric energy equation

A

gpe (water behind dam)
-> kinetic energy (water)
-> kinetic energy (turbine)
-> electrical energy (geneator)

49
Q

hydroelectric energy explained

A
  • reservoir water stores GPE
  • water runs down passageway high speed -> GPE->KE
  • moving water turns blade of turbine KE of water -> KE of turbine
  • KE of blades -> EE in generator
50
Q

impact of hydroelectric energy

A
  • water may flood -> kills plants and animal\
  • new fishing spots
51
Q

wind energy

A

wind turbines convert energy from wind to EE

52
Q

wind energy equation

A
  • kinetic energy (wind)
    -> kinetic energy (turbine)
    -> electrical energy (generator)
53
Q

wind energy explained

A
  • wind blows at wind turbine
  • kinetic energy of wind is transferred to to the blades of the turbine
  • blades rotate
  • generator connected generates electrical energy
54
Q

impact of wind energy

A
  • large plots of land had to be cleared to build wind farms
  • potential lost of wildlife/habitat
  • birds may die
  • nosie pollution
55
Q

geothermal energy

A

heat stored in earth
- harnessed to generate electrical energy

56
Q

geothermal energy equation

A
  • heat energy (earth’s core)
  • KE (steam)
  • KE (turbine)
  • EE (generator)
57
Q

geothermal energy explained

A
  • goethermal plant uses heat from deep inside earth’s core generate steam
  • powers turbine
  • produce energy
58
Q

goethermal process

A
  • cooled water is pumped in hot rocks inside earth’s core
  • cooled water is heated by geothermal energy and turns into steam
  • hot water and steam is pumped to earth’s surface
  • steam is sued to power turbine and generator to generate EE
59
Q

impact of geothermal

A
  • require cleaning of land
  • destroy habitats
  • traces of toxic elements burried are drawn out
60
Q

biofuels

A
  • animal waste/plant materials that cannot be eated
  • recycling food waste (cooking oil)
61
Q

biofuels equation

A
  • cpe (biofuel)
  • heat energy
  • KE (vehicle)
62
Q

biofuels explained

A
  • plants are grown
  • plant (waste) used to make biofuels
  • biofuels mix with other fuels + power vehicles
    -carbon dioxide released when fuel burns is absorbed by plants
63
Q

impact of biofuels

A
  • burning biofuels release air pollutants
  • plants used can be grown again quickly
  • biofuels can be used for cooking
  • reduce waste
  • balance amount of CO2 released with CO2 absorbed
64
Q

nuclear energy

A
  • energy harnessed from nucleus of an atom
  • obtained through nuclear reactions -> EE
65
Q

nuclear energy equation

A
  • nuclear energy (atom)
  • heat energy
  • KE (turbine)
  • EE (generator)
66
Q

nuclear energy explained

A
  • nuclear power plants generate EE using heavy atoms
  • atoms split into smaller ones, large heat is released
  • used to boil water
  • steam produce powers turbines to generate EE
67
Q

nuclear energy impact

A
  • health risks
  • nuclear accidents

yr 2 science eye (12 decks)

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