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P2 Flashcards

1
Q

*Describe movement of air craft when resultant is zero (1)

A

Constant speed

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2
Q

*As the aircraft moves along the runway to take off, its acceleration decrease even through the force from the engines is constant. Why. (2)

A

As speed increases, air resistance increasesReduce resultant force.

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3
Q

How is velocity different from the speed (1)

A

Velocity includes direction

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4
Q

The total momentum of the 2 cars was not conserved. What does this mean (1)

A

Momentum before not equal momentum after

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5
Q

Why constant force seat belt better for car driver (2)

A

Force = change of momentum/time takenSo the smaller the force, the smaller the momentum in the same time

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6
Q

Connection between thinking distance and speed (1)

A

Directly proportional

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7
Q

Do you think data given in Highway Code is likely to be reliable (1)

A

Data would have been checked

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8
Q

Relationship between stopping distance thinking and braking (1)

A

Stop = think + brake

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9
Q

2 factors increase braking distance (2)

A

Road conditionsWorn tyresRain

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10
Q

Why toy accelerates upwards when fan rotates faster (2)

A

Greater change in momentumForce up greater than force down

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11
Q

Explain how the flexible polystyrene base helps to protect the toy from being damaged when it crashes into the ground. (3)

A

increase the time to stopdecrease rate of change in momentumreducing the force on the toy

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12
Q

Why is the kinetic of each passenger different (1)

A

Each has different mass

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13
Q

Why B has best cushioning system (3)

A

Smallest impact forceOn all surfaces

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14
Q

Why data from robot more reliable than humans (1)

A

Can be repeated

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15
Q

Explain in terms of gravity and air resistance why ball bearing accelerates at first but then falls at constant speed (3)

A

Initially gravity greater than airAs speed increase air increaseWhen gravity equal air speed is constant

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16
Q

What name is given to constant speed reached by ball

A

Terminal velocity

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17
Q

What happens to kinetic energy lost (1)

A

Transformed into heat energy

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18
Q

Why velocity time graph shown as line graph instead of bar (1)

A

Velocity and time are continuous variables

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19
Q

Why C represents the forces acting when the cyclist is travelling at constant velociy (3)

A

Velocity not changingForces must be balanced

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20
Q

Define momentum is conserved (1)

A

Momentum before equal after

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21
Q

Why in collision momentum not always conserved (1)

A

An external force acts on colliding objects

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22
Q

How and why does kinetic energy of skier going downwards change (2)

A

It increasesGpe turns into ke

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23
Q

How does graph suggest B is on alcohol (1)

A

Greater stopping distance

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24
Q

How graphs show cars have same deceleration (1)

A

Same gradient

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25
Q

Why doubling diameter of blades more than doubles power output of turbine (1)

A

Ke more than doublesMass of air more than doubles

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26
Q

What form of energy stored in stretched spring (1)

A

Elastic potential

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27
Q

*Why parachutist reaches terminal velocity and why opening parachute reduces terminal velocity (6)

A

1On leaving plane only force acting is gravityAs para falls air actsWeight more than airTherefore para acceleratesAs speed increase air increase2Open para increas SaAir more than weightPara deceleratesLower velocity means reduced airAir equal weight but lower tv

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28
Q

*Speed less than calculated why (3)

A

Work is doneAgainst friction between miner and slideCausing energy transferred to surroundings

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29
Q

How streamlined help speed (2)

A

Air smallerTherefore reach higher speed

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30
Q

Why force needed greater (1)

A

Need o overcome resistant forces

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31
Q

Thinking distance (1)

A

Distance vehicle travels during drivers reaction time

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32
Q

2 factors affect thinking distance (2)

A

TirednessSpeedAge Alcohol

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33
Q

Applying brakes increase its temp why (2)

A

FrictionDecrease ke increase thermal

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34
Q

Resultant force (1)

A

Single force that has the same effect as all forces acting on an object

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35
Q

How can current through material be changed (1)

A

Change no of cells

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36
Q

One error reduced accuracy (1)

A

Measure voltage incorrectly

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37
Q

How reliability improved (1)

A

Repeat readings

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38
Q

What happens to cause driver to become charged (2)

A

Clothing and seat rub togetherElectrons transfer from driver to seat

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39
Q

Why important scientists control humidity (1)

A

How wet air is affects charge

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40
Q

Does table show that charge on driver always less when wear cotton (1)

A

No many materials not listed

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41
Q

Direct current (1)

A

Current only flows one way

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42
Q

Why bigger current needed when uphill (2)

A

More force neededWork done against gravity

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43
Q

What effect travelling uphill has on range of scooter (1)

A

Reduces it

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44
Q

How fission lead to chain reaction (2)

A

Released neutrons absorbed by further uranium nucleiMore neutrons released when new nuclei split

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45
Q

How mass number change when nucleus absorb neutron (1)

A

Increase by 1

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46
Q

What happens when control rods lowered into reactor (2)

A

More neutrons absorbedChain reaction slows downLess energy released

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47
Q

Mass no (2)

A

No of p and n inside an atom

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48
Q

When radon 222 emit alpha change into polonium 218 how nucleus diff (1)

A

2 fewer neutrons and 2 fewer protons

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49
Q

Unnatural background radiation (1)

A

Nuclear power

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50
Q

Concerned about radiation dose in germany (2)

A

No only staying 2 weeksTotal exposure well under lowest limit for causing cancer

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51
Q

Describe how potential of live varies with respect to neutral (2)

A

AlternatesBetween positive and negative

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52
Q

What B shows (1)

A

Pd between neutral and earth

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53
Q

Advantage of having all droplets of glue negatively charged (2)

A

Droplets will repel each otherEven coating of glue on paper

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54
Q

Why sand moves towards sticky paper (2)

A

Sand positiveRepelled from positive plate

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55
Q

Why current pass through each element same (2)

A

Connected in series

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56
Q

In series how pd shared (1)

A

Equally

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57
Q

How electrostatic precipitator separates soot from waste gases (3)

A

Soot pass negative gridAttracted to positive plate

58
Q

What must happen to cause spark jumpnfrom dome to earthed conductor (2)

A

Charge must increaseProducing large enough pd between dome and earthed conductor

59
Q

Diff between ac and dc (2)

A

Dc flow only in 1DAc change direction

60
Q

No of protons (1)

A

Atomic no

61
Q

Uranium 248 decays into thorium 234 what radiation emitted (1)

A

Alpha

62
Q

Why atom decays by emitting alpha or beta become diff element (1)

A

No of proton changes

63
Q

Diff between plum pudding and new (4)

A

NMass concentrated at nucleusPositive only at small part of atomElectrons orbit centreMainly empty spacePMass evenly distributedPositive spread throughout atomElectrons embedded in positiveSolid mass

64
Q

Why some alpha deflected backwards (2)

A

Nucleus must be positive to repel alphaNucleus small so few deflected

65
Q

Why Rutherford convince others plum wrong (1)

A

100 000 measurements takenFinding cannot be explained by plum

66
Q

Why atom no overall charge (2)

A

Sane no of protons and electronsCancels out

67
Q

How uranium 235 diff from 238 (1)

A

3 fewer neutrons

68
Q

What absorbed in fission (1)

A

Neutron

69
Q

Ruler negative because (1)

A

Gain electrons

70
Q

How show ruler charged (1)

A

Attracts positive object

71
Q

Why measurement made with person standing on plastic (2)

A

Plastic is an insulatorKeeps charge on person

72
Q

Why important all wore same clothing (1)

A

Type of clothing could affect charge

73
Q

Why not necessary to increase precision (1)

A

Enough precision to tell diff between materials

74
Q

Why investigation may cause manufacturer change material of car seat (2)

A

People less likely to get shockedMaterial normally used has value above pd likely to cause shockUse material reduces pd

75
Q

Why good idea electricians wear rubber (2)

A

Increases overall resistanceIn event of shock gives smaller current

76
Q

Frequency of mains electricity in UK (1)

A

50Hz

77
Q

Is frequency in UK mains safe (1)

A

No has lowest current at which people cannot let go

78
Q

If fault makes metal case live earth and fuse protect from electric shock how (2)

A

Current flows through live wire to earthCurrent cause fuse to melt

79
Q

Process nuclear fusion (2)

A

2 nuclei of light elements joinForming heavier nucleus

80
Q

Where nuclear fusion happen naturally (1)

A

Stars

81
Q

Why scientists continue to try to develop nuclear fusion reactor (1)

A

Give another source energyUnlimited fuel supplies

82
Q

Why scientists thought evidence unreliable (1)

A

Data not validNot reproducible

83
Q

Why people believe journal not newspaper (1)

A

Newspaper journalist might not have scientific backgroundMay simplify ideasCannot trust journalists

84
Q

Th 230 90 decays Ra 226 88 what radiation why (3)

A

AlphaMass no goes down by 4 Atomic no goes down by 2

85
Q

Why light sensing circuit not used to measure values of light intensity (2)

A

Light intensity value not reliableDue to variation in resistance value

86
Q

Why students hair stand when generator switched on (2)

A

Hair negativeNegative repel

87
Q

Rate of flow of charge (1)

A

Current

88
Q

Not possible to give exact figure of deaths caused by radon why (1)

A

Other factors involved

89
Q

Why measurements taken over 3 months using detectors in diff rooms (1)

A

Find an average

90
Q

Why glass become positive (2)

A

Electrons transferTo the cloth

91
Q

Why TV screen become dusty (2)

A

TV screen becomes positiveAttracts negative dust

92
Q

Why important paper heated (1)

A

Melt toner

93
Q

Name substance used as fuel in some nuclear reactors (2)

A

PlutoniumUranium

94
Q

Electric current (1)

A

Flow of electrons

95
Q

Ion (1)

A

Atom that has lost or gained electrons

96
Q

Why plastic bottles become charged (2)

A

Friction between bottle and beltCharge transfer between them

97
Q

Earthing conveyor belt with wire not solved problem why (1)

A

Belt is rubber

98
Q

Natural source of background radiation (1)

A

RocksFood drinkCosmic rays

99
Q

What is important about no of people in group (1)

A

Same

100
Q

What data would scientists compare to conclude x rays increase risk of cancer (1)

A

How many in each group get cancer

101
Q

Why dangerous if replace fuse with foil (2)

A

Larger current still flowFault not repairedFoil not meltWiring may cause fire

102
Q

*Person may receive higher than average dose of radiaon why (2)

A

FlyingWork in nuclear power station

103
Q

*Ethical use animals in testing (2)

A

No choice cruelSufferBetter animals than manTest lead to health improvement

104
Q

*Pd

A

Energy transferred per coulomb of charge

105
Q

*Why resistance of filament increase as pd increase (3)

A

Metals contain free electronsAs temp increase ion vibrate fasterElectrons collide more with ions

106
Q

*Diff be wee protostar and main sequence star (2)

A

Proto lower tempFusion reactions not started

107
Q

*How elements formed (3)

A

By fusionOf h to heElements heavier than iron formed in supernova

108
Q

*Scale only prediction why (1)

A

Resistance changesAffected by many factors

109
Q

*Why not use scales after drinking water (2(

A

Gives inaccurate valueHigh water content changes body resistance

110
Q

*Compare RCCB and fuse (2)

A

RCCB detect diff between live and neutralFuse melts

111
Q

Why readings diff (1(

A

Random process

112
Q

Why stars stable (1)

A

Forces balanced

113
Q

Rate of fusion in large star is ….. Than small star explain (3)

A

FasterLarger stars have shorter Ms period so faster fusionUse up h at fasster rate

114
Q

What happens to star much bigger than sun once reached end Ms period (6)

A

Star runs out of hExpandsCoolsRed supergiant outer layers expandSupernova elements heavier than iron formed core shrinksNeutron star mass large enough core collapses to form black hole

115
Q

Why diode cause trace change (2)

A

Diode has large resistance in one directionSo stops current flow in one direction

116
Q

What happens to cause RCCB to switch circuit off (2)

A

Current flows to earthThrough copper braidRCCB detects diff between live and neutral wire

117
Q

Advantage of RCCB switch off circuit than fuse (1)

A

Can be reset

118
Q

How increase in temp of soil affect thermistor (2)

A

Increases temp of thermistorChanges resistanceDecreases resistance

119
Q

Why variable resistor included (1)

A

To obtain range of pd values

120
Q

Resistance of bulb increase as of increase why (1)

A

Temp increases

121
Q

How energy from fission used to generate electricity (3)

A

Energy used to heat h2oProduce high pressure streamSteam drives turbine generator

122
Q

Why lowering control rods reduce energy released from nuclear fuel (2)

A

Neutrons absorbed by rodsFewer neutronsChain reaction slow down

123
Q

Why advice given (26

A

Limits amount of iodine absorbedSo reduce risk of cancer

124
Q

Why not safe to plug in (2)

A

Current exceeds max safe current for 2.5mm wireWire would melt

125
Q

Describe structure of cable (3)

A

Contains live neutral and earth wireCross sectional are 4mmWire insulated

126
Q

Why child becomes charged when go down the slide (2)

A

Friction between child’s clothing and slideCauses electron transfer

127
Q

Going down slide make child’s hair stand conclusion and reason (2)

A

All charges on hair sameCharge repelling

128
Q

Why child not charged if slide metal (1)

A

Charge would pass though metal to earthMetal is conductor

129
Q

What after red supergiant (1)

A

Supernova

130
Q

Why scientists can only estimate (1)

A

Not have tech

131
Q

Why possible for scientists measure later (1)

A

Advances tech

132
Q

What happen after Ms to become black dwarf (5)

A

Star expandsBecome red giantHeavier elements formed by fusionStar shrinksBecome white dwarfStar fadesStar stops emitting energy

133
Q

Cyclist pedal constant (6)

A

First friction greater than airAcceleratesVelocity increasesAir increase with velocityResultant decreaseAccelerate but smallerSo velocity increase but lower rateAir increaseAcceleration decreaseAir equal frictionResultant 0 acceleration 0Velocity increase until TV

134
Q

Why important ammeters have low resistance (1)

A

So ammeter affect current little as possible

135
Q

Advantage of using same units (1)

A

Common understanding

136
Q

Why when boarder jumps forwards board goes back (3)

A

Momentum conservedBefore jumping momentum of boarder and board is 0After boarder has momentum so board must have equal momentum backwards

137
Q

What happens in fission (1)

A

Nuclei split

138
Q

When produced (1)

A

Reactor

139
Q

Half life (1)

A

Average time taken for no of nuclei to halve

140
Q

Risk using radioactive substance as tracer (2)

A

Radiation cause ionisationMay cause cancer harm living cells

141
Q

Doctors still use radio as tracers why (1)

A

Benefit greater than risk

142
Q

How RCCB operate (1)

A

Detects diff between current in live and neutral

2 (6 decks)

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