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AS levels Resurrection > P 4. Energy Concepts Revamp > Flashcards

P 4. Energy Concepts Revamp Flashcards

1
Q

Define work
(2-way + 2 things)

A
  • Product of force and distance moved in direction of force
  • when force is constant
  • Scalar quantity
  • Measured in Joules (J)
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2
Q

Work done expressed in a formula?

A

Work done = force x distance

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3
Q

Work done formula expressed in symbols?

A

J = N x m

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4
Q

Define J
(Work done formula)

A

Joules
(J)

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5
Q

Define N
(Work done formula)

A

Newtons
(N)

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6
Q

Define m
(Work done formula)

A

Metres
(m)

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7
Q

Define energy
(3 things)

A
  • The ability to do work
  • Scalar quantity
  • Measured in Joules (J)
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8
Q

1J is the….?
(The joule in the work done formula)
(3-way)

A
  • work done when
  • a Force of 1N moves its point of application
  • 1m in the direction of that Force
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9
Q

1J = ?

A

1 Nm

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10
Q

1J in base units?
(3 steps)

A
  1. F = ma
  2. = kgms-2
  3. 1kgm-2s-2
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11
Q

Show an equation is homogeneous?

A

If the case calls

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12
Q

What are the 2 formulas for work done?
(1 of them is in the data booklet)

A
  • W = Fx
  • W = Fxcosθ
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13
Q

Explain work done = energy
(2 things + 2-way)

A
  • Work be done moving an object
  • Same with stopping an object
  • Energy at start transferred to work done stopping object
  • when it comes to rest (at ground level)
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14
Q

What’s the jig with “ground level” with work done = energy?
(2 things)

A
  • Object may still have GPE (Ep)
  • if not at ground level
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15
Q

What is the work energy relationship?

A
  • When object slows/speeds up
  • work being done on object
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16
Q

How do u find the work done from object slowing/speeding up?
(3-way)

A
  • Difference in the initial,
  • and final kinetic energies
  • of the object
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17
Q

How do u find the braking force acting on an object?
(2 things)

A
  • Use W = F x D
  • Rearrange for F
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18
Q

What does it mean if “total energy is conserved even though there is a loss in kinetic energy”?
(2-way)

A
  • Work done slowing the car
  • is transferred to thermal energy
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19
Q

Work = change in Kinetic energy expressed as in symbols?
(It’s in data booklet)

A

Fx = ½mv2 - ½mu2

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20
Q

What’s Fx = ½mv2 - ½mu2 used for?

A

Finding the kinetic energy at the end of journey

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21
Q

How do u find the average resistive force?
(5 ways, step by step)

A
  • Use equation to find GPE
  • GPE = KE + wd against friction
  • Rearrange for wd
  • Then W = FD
  • Rearrange for F
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22
Q

What is kinetic energy?
(2-way)

A
  • The energy possessed
  • by a moving object
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23
Q

What’s the equation to find kinetic energy?
(In data booklet)

A

Ek = ½mv2

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24
Q

KE equation expressed in words?

A

Kinetic energy = ½ x mass x speed2

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25
Q

Define Ek?
(KE equation)

A

Joules
(J)

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26
Q

Define m
(KE equation)

A

Mass
(kg)

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27
Q

Define v
(KE equation)

A

Velocity
(ms-1)

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28
Q

What is Gravitational potential energy? (Ep)
(3-way)

A
  • Energy possessed by an object
  • due to its position
  • or height about the Earth
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29
Q

What’s the equation to find gravitational potential energy?
(In data booklet)

A

Ep = mgh

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30
Q

GPE equation expressed in words?

A

Gravitational energy = mass x gravitational field strength x height

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31
Q

Define Ep?
(GPE equation)

A

Joules
(J)

32
Q

Define m
(GPE equation)

A

Mass
(kg)

33
Q

Define g
(In data booklet)
(GPE equation)

A

Gravity
(9.81ms-2)

34
Q

Define h
(GPE equation)

A

Height
(m)

35
Q

How to derive GPE?
(4-way)

A
  • Wd = f x d
  • f = ma
  • Moving thru air ∴ a = g
  • Wd = m x g x h
36
Q

What is elastic potential energy?
(4-way)

A
  • Potential energy stored
  • as a result of deformation
  • of an elastic object
  • aka stretching of a spring
37
Q

Define an “elastic object”?
(2 things)

A
  • Can become as it was
  • return from deformation
38
Q

How to find EPE of a wire?

A

EPE = ½Fx

39
Q

Define F
(EPE equation)

A

Average force
(N)

40
Q

Define x
(EPE equation)

A

Extension
(m)

41
Q

But what happens if u sub in force against extension gradient in EPE equation?

A

U get work done needed to stretch a spring

42
Q

How to find the work done needed to stretch a spring?

A

Work = ΔPE = ½kx2

43
Q

Define k
(Wd needed to stretch a spring)

A

Spring constant
(k…)

44
Q

Define x
(Wd needed to stretch a spring)

A

Distance the stretch of the spring is
(m)

45
Q

When talking about the conservation of energy of an object, what must be considered?
(3 things)

A
  • Changes in kinetic energy
  • Changes in gravitational energy
  • When to state it’s max or zero energy
46
Q

A ball is being thrown up, explain point A
(2 things)

A
  • KE decreases, GPE increases
  • KE > GPE
47
Q

A ball is being thrown up, explain point B
(2 things)

A
  • KE decreases, GPE increases
  • GPE > KE
48
Q

A ball is being thrown up, explain point C
(2 things)

A
  • KE = zero
  • GPE = max
49
Q

A ball is being thrown up, explain point D
(2 things)

A
  • GPE decreases, KE increases
  • GPE > KE
50
Q

A ball is being thrown up, explain point E
(2 things)

A
  • GPE decreases, KE increases
  • KE > GPE
51
Q

When ball being thrown up, how come at point C the KE is zero?
(3 things)

A
  • Object at its highest point
  • Briefly has zero velocity
  • Therefore zero KE
52
Q

What does the conservation of energy in a system tell us?

A

Initial energy for a system = final energy for a system

53
Q

How do u work out energy lost due to friction?
(2 possible methods)

A

KE = GPE + heat + sound
GPE = KE + heat + sound

54
Q

How to find force/distance of energy lost due to friction?
(2-way)

A
  • Heat + sound = work done (Wf)
  • Wf = Fx
55
Q

Define power
(3 things)

A
  • The rate of doing Work
  • Scalar quantity
  • Measured in watts (W) or Js-1
56
Q

1 Watt = ?

A

1Js-1

57
Q

1Js-1 = ?

A

1W

58
Q

The equation for power?
(In data booklet)

A

P = W/t

59
Q

Define w
(Power equation)

A

Energy
(J)

60
Q

Define t
(Power equation)

A

Seconds
(s)

61
Q

What’s the “better” power equation?
(Not in data booklet)

A

P = Fv

62
Q

Define F
(“better” power equation)

A

Force
(N)

63
Q

Define v
(“better” power equation)

A

Velocity
(ms-1

64
Q

Show how fv = w/t is homogenous
(4-way)

A
  1. fv = w/t
  2. maD/t = ½mv2/t
  3. kgms-2ms-1 = kgm2s-2s-1
  4. kgm2s-3 = kgm2s-3
65
Q

What’s the FIRST way to find efficiency %?

A

% Efficiency = (useful energy output/total energy input) x 100%

66
Q

What’s the SECOND way to find efficiency &?

A

& Efficiency = (useful power output/total power input) x 100%

67
Q

What are Sankey diagrams used for?

A
  • Show efficiency
  • by which the width of the arrow
  • is the % of energy
68
Q

Define the conservation of energy?
(5-way B|)

A
  • Energy cannot be created or destroyed
  • just transferred from one form
  • to another
  • or transferred from one place
  • to another
69
Q

What is chemical energy?
(2-way + 1 thing)

A
  • Energy stored in mixtures of chemicals
  • or in chemical compounds
    e.g. All fuels (coal, oil, gas) store chemical energy (potential)
70
Q

What is electrical energy?
(3-way)

A
  • Energy transferred in electrical circuits
  • by the motion of charger carriers
  • such as electrons (kinetic)
71
Q

What is radiant energy?
(2 things)

A
  • Energy carried by all types of electromagnetic waves
  • i.e. electromagnetic spectrum n stuff (kinetic)
72
Q

What is internal energy?
(4-way)
(Very familiar)

A
  • Energy possessed by a body due to
  • the random distribution of
  • kinetic and potential energies
  • of the molecules which make it up
73
Q

What is thermal/heat energy

A

Energy due to temperature of an object (kinetic)

74
Q

What is sound energy?
(2 things)

A
  • Energy produced by vibrating objects
    e.g. musical instruments, speakers
75
Q

Past paper questions shall be there

A

.

AS levels Resurrection (22 decks)

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