P2 Flashcards
(142 cards)
1
Q
*Describe movement of air craft when resultant is zero (1)
A
Constant speed
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.
3
Q
How is velocity different from the speed (1)
A
Velocity includes direction
4
Q
The total momentum of the 2 cars was not conserved. What does this mean (1)
A
Momentum before not equal momentum after
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
6
Q
Connection between thinking distance and speed (1)
A
Directly proportional
7
Q
Do you think data given in Highway Code is likely to be reliable (1)
A
Data would have been checked
8
Q
Relationship between stopping distance thinking and braking (1)
A
Stop = think + brake
9
Q
2 factors increase braking distance (2)
A
Road conditionsWorn tyresRain
10
Q
Why toy accelerates upwards when fan rotates faster (2)
A
Greater change in momentumForce up greater than force down
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
12
Q
Why is the kinetic of each passenger different (1)
A
Each has different mass
13
Q
Why B has best cushioning system (3)
A
Smallest impact forceOn all surfaces
14
Q
Why data from robot more reliable than humans (1)
A
Can be repeated
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
16
Q
What name is given to constant speed reached by ball
A
Terminal velocity
17
Q
What happens to kinetic energy lost (1)
A
Transformed into heat energy
18
Q
Why velocity time graph shown as line graph instead of bar (1)
A
Velocity and time are continuous variables
19
Q
Why C represents the forces acting when the cyclist is travelling at constant velociy (3)
A
Velocity not changingForces must be balanced
20
Q
Define momentum is conserved (1)
A
Momentum before equal after
21
Q
Why in collision momentum not always conserved (1)
A
An external force acts on colliding objects
22
Q
How and why does kinetic energy of skier going downwards change (2)
A
It increasesGpe turns into ke
23
Q
How does graph suggest B is on alcohol (1)
A
Greater stopping distance
24
Q
How graphs show cars have same deceleration (1)
A
Same gradient
25
Why doubling diameter of blades more than doubles power output of turbine (1)
Ke more than doublesMass of air more than doubles
26
What form of energy stored in stretched spring (1)
Elastic potential
27
*Why parachutist reaches terminal velocity and why opening parachute reduces terminal velocity (6)
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
28
*Speed less than calculated why (3)
Work is doneAgainst friction between miner and slideCausing energy transferred to surroundings
29
How streamlined help speed (2)
Air smallerTherefore reach higher speed
30
Why force needed greater (1)
Need o overcome resistant forces
31
Thinking distance (1)
Distance vehicle travels during drivers reaction time
32
2 factors affect thinking distance (2)
TirednessSpeedAge Alcohol
33
Applying brakes increase its temp why (2)
FrictionDecrease ke increase thermal
34
Resultant force (1)
Single force that has the same effect as all forces acting on an object
35
How can current through material be changed (1)
Change no of cells
36
One error reduced accuracy (1)
Measure voltage incorrectly
37
How reliability improved (1)
Repeat readings
38
What happens to cause driver to become charged (2)
Clothing and seat rub togetherElectrons transfer from driver to seat
39
Why important scientists control humidity (1)
How wet air is affects charge
40
Does table show that charge on driver always less when wear cotton (1)
No many materials not listed
41
Direct current (1)
Current only flows one way
42
Why bigger current needed when uphill (2)
More force neededWork done against gravity
43
What effect travelling uphill has on range of scooter (1)
Reduces it
44
How fission lead to chain reaction (2)
Released neutrons absorbed by further uranium nucleiMore neutrons released when new nuclei split
45
How mass number change when nucleus absorb neutron (1)
Increase by 1
46
What happens when control rods lowered into reactor (2)
More neutrons absorbedChain reaction slows downLess energy released
47
Mass no (2)
No of p and n inside an atom
48
When radon 222 emit alpha change into polonium 218 how nucleus diff (1)
2 fewer neutrons and 2 fewer protons
49
Unnatural background radiation (1)
Nuclear power
50
Concerned about radiation dose in germany (2)
No only staying 2 weeksTotal exposure well under lowest limit for causing cancer
51
Describe how potential of live varies with respect to neutral (2)
AlternatesBetween positive and negative
52
What B shows (1)
Pd between neutral and earth
53
Advantage of having all droplets of glue negatively charged (2)
Droplets will repel each otherEven coating of glue on paper
54
Why sand moves towards sticky paper (2)
Sand positiveRepelled from positive plate
55
Why current pass through each element same (2)
Connected in series
56
In series how pd shared (1)
Equally
57
How electrostatic precipitator separates soot from waste gases (3)
Soot pass negative gridAttracted to positive plate
58
What must happen to cause spark jumpnfrom dome to earthed conductor (2)
Charge must increaseProducing large enough pd between dome and earthed conductor
59
Diff between ac and dc (2)
Dc flow only in 1DAc change direction
60
No of protons (1)
Atomic no
61
Uranium 248 decays into thorium 234 what radiation emitted (1)
Alpha
62
Why atom decays by emitting alpha or beta become diff element (1)
No of proton changes
63
Diff between plum pudding and new (4)
NMass concentrated at nucleusPositive only at small part of atomElectrons orbit centreMainly empty spacePMass evenly distributedPositive spread throughout atomElectrons embedded in positiveSolid mass
64
Why some alpha deflected backwards (2)
Nucleus must be positive to repel alphaNucleus small so few deflected
65
Why Rutherford convince others plum wrong (1)
100 000 measurements takenFinding cannot be explained by plum
66
Why atom no overall charge (2)
Sane no of protons and electronsCancels out
67
How uranium 235 diff from 238 (1)
3 fewer neutrons
68
What absorbed in fission (1)
Neutron
69
Ruler negative because (1)
Gain electrons
70
How show ruler charged (1)
Attracts positive object
71
Why measurement made with person standing on plastic (2)
Plastic is an insulatorKeeps charge on person
72
Why important all wore same clothing (1)
Type of clothing could affect charge
73
Why not necessary to increase precision (1)
Enough precision to tell diff between materials
74
Why investigation may cause manufacturer change material of car seat (2)
People less likely to get shockedMaterial normally used has value above pd likely to cause shockUse material reduces pd
75
Why good idea electricians wear rubber (2)
Increases overall resistanceIn event of shock gives smaller current
76
Frequency of mains electricity in UK (1)
50Hz
77
Is frequency in UK mains safe (1)
No has lowest current at which people cannot let go
78
If fault makes metal case live earth and fuse protect from electric shock how (2)
Current flows through live wire to earthCurrent cause fuse to melt
79
Process nuclear fusion (2)
2 nuclei of light elements joinForming heavier nucleus
80
Where nuclear fusion happen naturally (1)
Stars
81
Why scientists continue to try to develop nuclear fusion reactor (1)
Give another source energyUnlimited fuel supplies
82
Why scientists thought evidence unreliable (1)
Data not validNot reproducible
83
Why people believe journal not newspaper (1)
Newspaper journalist might not have scientific backgroundMay simplify ideasCannot trust journalists
84
Th 230 90 decays Ra 226 88 what radiation why (3)
AlphaMass no goes down by 4 Atomic no goes down by 2
85
Why light sensing circuit not used to measure values of light intensity (2)
Light intensity value not reliableDue to variation in resistance value
86
Why students hair stand when generator switched on (2)
Hair negativeNegative repel
87
Rate of flow of charge (1)
Current
88
Not possible to give exact figure of deaths caused by radon why (1)
Other factors involved
89
Why measurements taken over 3 months using detectors in diff rooms (1)
Find an average
90
Why glass become positive (2)
Electrons transferTo the cloth
91
Why TV screen become dusty (2)
TV screen becomes positiveAttracts negative dust
92
Why important paper heated (1)
Melt toner
93
Name substance used as fuel in some nuclear reactors (2)
PlutoniumUranium
94
Electric current (1)
Flow of electrons
95
Ion (1)
Atom that has lost or gained electrons
96
Why plastic bottles become charged (2)
Friction between bottle and beltCharge transfer between them
97
Earthing conveyor belt with wire not solved problem why (1)
Belt is rubber
98
Natural source of background radiation (1)
RocksFood drinkCosmic rays
99
What is important about no of people in group (1)
Same
100
What data would scientists compare to conclude x rays increase risk of cancer (1)
How many in each group get cancer
101
Why dangerous if replace fuse with foil (2)
Larger current still flowFault not repairedFoil not meltWiring may cause fire
102
*Person may receive higher than average dose of radiaon why (2)
FlyingWork in nuclear power station
103
*Ethical use animals in testing (2)
No choice cruelSufferBetter animals than manTest lead to health improvement
104
*Pd
Energy transferred per coulomb of charge
105
*Why resistance of filament increase as pd increase (3)
Metals contain free electronsAs temp increase ion vibrate fasterElectrons collide more with ions
106
*Diff be wee protostar and main sequence star (2)
Proto lower tempFusion reactions not started
107
*How elements formed (3)
By fusionOf h to heElements heavier than iron formed in supernova
108
*Scale only prediction why (1)
Resistance changesAffected by many factors
109
*Why not use scales after drinking water (2(
Gives inaccurate valueHigh water content changes body resistance
110
*Compare RCCB and fuse (2)
RCCB detect diff between live and neutralFuse melts
111
Why readings diff (1(
Random process
112
Why stars stable (1)
Forces balanced
113
Rate of fusion in large star is ..... Than small star explain (3)
FasterLarger stars have shorter Ms period so faster fusionUse up h at fasster rate
114
What happens to star much bigger than sun once reached end Ms period (6)
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
Why diode cause trace change (2)
Diode has large resistance in one directionSo stops current flow in one direction
116
What happens to cause RCCB to switch circuit off (2)
Current flows to earthThrough copper braidRCCB detects diff between live and neutral wire
117
Advantage of RCCB switch off circuit than fuse (1)
Can be reset
118
How increase in temp of soil affect thermistor (2)
Increases temp of thermistorChanges resistanceDecreases resistance
119
Why variable resistor included (1)
To obtain range of pd values
120
Resistance of bulb increase as of increase why (1)
Temp increases
121
How energy from fission used to generate electricity (3)
Energy used to heat h2oProduce high pressure streamSteam drives turbine generator
122
Why lowering control rods reduce energy released from nuclear fuel (2)
Neutrons absorbed by rodsFewer neutronsChain reaction slow down
123
Why advice given (26
Limits amount of iodine absorbedSo reduce risk of cancer
124
Why not safe to plug in (2)
Current exceeds max safe current for 2.5mm wireWire would melt
125
Describe structure of cable (3)
Contains live neutral and earth wireCross sectional are 4mmWire insulated
126
Why child becomes charged when go down the slide (2)
Friction between child's clothing and slideCauses electron transfer
127
Going down slide make child's hair stand conclusion and reason (2)
All charges on hair sameCharge repelling
128
Why child not charged if slide metal (1)
Charge would pass though metal to earthMetal is conductor
129
What after red supergiant (1)
Supernova
130
Why scientists can only estimate (1)
Not have tech
131
Why possible for scientists measure later (1)
Advances tech
132
What happen after Ms to become black dwarf (5)
Star expandsBecome red giantHeavier elements formed by fusionStar shrinksBecome white dwarfStar fadesStar stops emitting energy
133
Cyclist pedal constant (6)
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
Why important ammeters have low resistance (1)
So ammeter affect current little as possible
135
Advantage of using same units (1)
Common understanding
136
Why when boarder jumps forwards board goes back (3)
Momentum conservedBefore jumping momentum of boarder and board is 0After boarder has momentum so board must have equal momentum backwards
137
What happens in fission (1)
Nuclei split
138
When produced (1)
Reactor
139
Half life (1)
Average time taken for no of nuclei to halve
140
Risk using radioactive substance as tracer (2)
Radiation cause ionisationMay cause cancer harm living cells
141
Doctors still use radio as tracers why (1)
Benefit greater than risk
142
How RCCB operate (1)
Detects diff between current in live and neutral
