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Level 2 Science > Forces and Energy > Flashcards

Forces and Energy Flashcards

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1
Q

SI unit of force

A

Newton (N)

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2
Q

definition of a force

A

push or pull that
changes shape/size of obj.
moves/stops obj.
changes direction of moving obj.
slows down/speeds up moving obj.

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3
Q

what is used to measure force

A

force-meters
Newton meters (e.g. spring balance)

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4
Q

what is a contact force

A

forces acted between 2 objects physically touching

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5
Q

what is a non-contact force

A

forces acted between 2 objects not physically touching

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6
Q

5 contact forces

A

resistance
spring force
tension
applied force
normal contact force

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7
Q

3 non-contact forces

A

gravitational force
magnetic force
electrostatic force

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8
Q

what is normal contact force

A

force exerted on object due to its contact with another object

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9
Q

what is a gravitational field

A

region which a mass experiences a force due to gravitational attraction

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10
Q

what is a gravitational field strength

A

gravitational force acting per unit mass

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11
Q

formula of weight

A

W = mg (m = mass, g = gravitational field strength)

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12
Q

SI unit for weight

A

Newton (N)

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13
Q

what is friction

A

contact force that opposes motion or tendency for motion

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14
Q

why is there friction

A

microscopically, surfaces/objects are rough jagged
as 2 surfaces slide against each other, they grind and drag to create friction

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15
Q

3 benefits of friction

A

graphite pencil marks a mark on paper due to friction

warms hand when rubbed

friction between wheels and brakes slows down bicycles

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16
Q

3 downsides of friction

A

wears out rubber tyres

engines/axels may lose energy due to friction

air resistance slows down car

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17
Q

3 ways to reduce friction

A

lubricants
streamlined body to reduce air/water resistance
wheels/rollers/ball bearings (circular shape reduces C.S.A)

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18
Q

what is resultant force

A

single force that has same effect as 2 or more forces acting together

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19
Q

what is pressure

A

ratio of magnitude of force applied to area on which it is applied

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20
Q

SI unit of pressure

A

Pascal (Pa) or N/m²

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21
Q

formula of pressure

A

F (N)/A (m²)

22
Q

what is atmospheric pressure

A

pressure exerted by air in Earth’s atmosphere

23
Q

what is moment of a force

A

turning effect produced by force

24
Q

formula of moment of force

A

Moment of force = force (N) x perpendicular distance from pivot (m)

25
Q

SI unit of moment of force

A

Newton-metre (Nm)

26
Q

what is a pivot/fulcrum

A

point about which a force turns

27
Q

what does the Principle of Moments state

A

when obj. is in equilibrium
sum of clockwise moments about any point
is equal to sum of anti-clockwise moments about the same point

28
Q

what is energy

A

ability to do work

29
Q

SI unit of energy

A

Joule (J)

30
Q

what is potential energy

A

energy stored in a body due to its condition/position

31
Q

what is energy in action

A

energy that is in motion in a medium that has the ability to do work

32
Q

what is GPE

A

energy a body possesses due to its position relative to the ground

33
Q

3 points

what does GPE depend on

A

mass (m) of obj.
height (h) obj. is at
gravitational field strength (g) obj.is in

34
Q

what is EPE

A

energy stored in elastic obj. when push or pulled

35
Q

what is CPE

A

energy which holds the atoms and molecules of a substance together

this stored energy is released during chemical reactions

36
Q

what is NE

A

energy in the nucleus of an atom which holds protons and neutrons together
this energy is released during nuclear reactions

37
Q

what is nuclear fission

A

breaking down of a larger nucleus
by bombarding atom of a fuel with a neutron
splitting it into 2 smaller nuclei
and 2 or 3 neutrons to carry on reaction with another 2 or 3 fuel atoms
(used in nuclear bombs and nuclear power stations)

38
Q

what is nuclear fusion

A

fusing of 2 small nuclei
to form 1 larger, unstable nucleus
giving off energy in the form of a fast-moving neutron
(found in hydrogen bombs and stars)

39
Q

difference between CPE and NE

A

CPE: energy released when there is forming of bonds between atoms and molecules
NE: energy released when there is change in atomic structure of an element

40
Q

what is KE

A

energy a body possesses due to its motion

41
Q

what does KE depend on

A

mass (m) of obj.
speed (v) of obj.

42
Q

what is LE

A

energy which enables us to see and do work

43
Q

what is TE

A

energy which flows from a region of higher temperature to a region of lower temperature

44
Q

what is EE

A

energy made available by the flow of electric charges such as electrons and ions (most useful form of energy as it can convert to other forms easily)

45
Q

what is SE

A

energy produced by vibrations which can be detected by our ears

46
Q

3 points

what does the Principle of Conservation of Energy state

A

energy cannot be created nor destroyed

can be converted from 1 state to another/transferred from 1 body to another

total amount of energy will be same before and after change or transfer

47
Q

3 ways to save energy

A

take public transport
switch off appliances when not in use
use fans instead of air-conditioners

48
Q

SI unit of work

A

Joule (J)

49
Q

2 points

what conditions need to be met for work to be done

A

force acts on object

object moves in same direction as force

50
Q

formula of work

A

W = F x d (F = force, d = distance moved by obj. in direction of force)

Level 2 Science (15 decks)

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