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    Hi, guys! I made these notes whilst revising for unit 2 and unit 3. They cover most of the things you need to memorise for both exams so if you find it useful, just copy these down. Hope it helps

    acceleration - rate of change of velocity per unit per time (speeds up)deceleration - opposite of acceleration/ negative acceleration/ slows down
    velocity- speed in a given direction
    speed- distance/ time in m/s

    terminal velocity - air resistance/drag force is equal (and opposite to) the force making the object move e.g. gravity for a parachutist
    distance on velocity time graphs is the area inside the graph, underneath the line.
    work- energy transferred in joules e.g elastic potential energy on spring

    Hooke’s law - The extension of an elastic object is directly proportional to the force applied, provided the limit of proportionality is not exceeded.
    Limit of proportionality on a graph is when the line is no longer directly proportional.
    F= k x e
    f is force in newtons, k is n/m and extension is m.w = f x dwork is joules, force is newtons, distance is metres
    power = work/time
    power is watts, work is joules, time is secondskinetic energy - energy of a moving object due to its motiongravitational potential- energy of an object due to its position in a gravitational field weight- force (g, gravitational field strength) in Newtons N, downwards towards the centre of the earth.mass- kgweight- newtonsw = m x gweight in newtons, mass in kg and g is usually 10n/kg.
    P = m x vmomentum kg m/s = kg x m/s
    conservation of momentum - the total momentum before an event is equal to the total momentum after the eventmomentum also has directionthe longer the impact time, the more the impact force is reduced
    1. Seat belt reduces time taken to hit steering wheel.
    2. Air bag decreases time taken for face to hit steering wheel.
    thinking distance+braking distance = stopping distancethe faster the car travels, the longer the stopping distancetired, distraction, drinking alcohol, drugs can affect thinking distancemovement of elections (onto an insulator)gain of electrons= negativeloss of elections= positivebattery is more than one cellvoltmeter measures voltage/potential difference. ammeter measures current in amps, lamp lights up, switch controls current flow, fixed resistor lowers current, variable resistor lows current with different amounts, fuse, thermistor senses heat and e.g. adjusts heating -radiator, incubator, light dependant resistor (LDR) control resistance depending on light, light emitting diode made to make efficient lighting, diode allows current to flow only one way,resistance measured in ohmsI = Q/tcurrent in amps, charge is coulombs and the time is in seconds

    voltmeter measures potential difference
    potential difference is the work done per coulomb of charge that passes through the componentV = W/Qpotential difference in volts, work done in joules, charge in coulombs
    ohms law - current is directly proportional to the potential difference (temp is constant, fixed resistor). If you flip battery, the graph line is negative.V=IRpotential difference in volts, current in amps and resistance in ohms
    The total resistance is the sum of all the individual resistors or components.The total potential difference of the cells is the sum of the individual cells. (must be facing same way or will cancel out)The potential difference of the supply is shared between the components.The current is the same through each component.Parallel circuit: The potential difference across each component is the same.The current is different in different branches of the circuit. The total current through the whole circuit is the sum of the current through the separate components. The higher the resistance, the lower the current.LDR - negative correlation for resistance and light intensityuses: automatic lights, camera shutters, fridgesThermistor - negative correlate for temperature and resistanceuses: automatic heating systems, homes, incubatorsLED - light emitting diode - efficientcurrent and potential difference through lamp; graph is s shapeddiode only allows current in one direction, flip battery and it’ll stay at 0Temperature through current: free electrons flow through metal, hotter, atoms/ions gains energy, more vibrations, more frequent collisions, more successful collisionsElectric current -> direct current D.C (e.g. runs of battery)-> alternating current A.C (plug sockets, supplies frequency of 50 Hz and voltage of 230V in UK)the frequency of an ac supply can be determined from an oscilloscope trace using the equation f = 1/Tf is frequency in Hz, T is time in secondsperiod - time taken for 1 cycle3 core cablecopper better for conduction electricityplug has tough plastic case and it insulates the electricity, the plastic cable doesn’t break easily, cable grip/cord grip makes sure the cables don’t go out of place, fuse melts (blows) if the current is too high, brown wire (right) is live wire, blue wire is neutral wire, green and yellow wire is earth wire, and blue wire is neutral, wires are insulated with plastic cover to avoid them touching each other. 2 core cable doesn’t have earth pin as the wires are well insulated (for appliances with non-metal outer casings)earth wire is connected to metal casing of appliance in case live wire came loose and touched the casing so that the current can be directed to the earth wire and sent back into the plug, into the ground.current flows through the earth wire, has a low resistance, current goes up, blows the fuse.RCCB- residual current circuit breaker (for more dangerous things e.g. lawn mower)it is much quicker, and can be re set. wire carrying a current -> warmerfilament lamp -> gets very hot -> energy wastedCFL, compact fluorescent lamp, less heat -> more efficient -> less wasted.p = e/tpower in watts, energy transferred in joules, time in seconds.
    p=VIpower in watts, potential different in volts, current in amps
    isotope- different number of neutronsradiation or radioactivity energy comes from the nucleusgeiger-muller tube measures radioactivity in counts per minutesbackground radiation is radiation that is present naturally in low amounts. 50% from radon gas in air, also comes from food and drink, rocks, ground, buildings, cosmic rays -> outer space, medical (x rays), nuclear reactors, air travel, nuclear accidents, nuclear weapons tests.rutherford and mars den thought atoms looked like plum puddings.experiment: alpha particles (2+) fired at thin gold foil in vacuum chamber, detector
    result: some were deflected and came straight back other than going straight through.
    • most alpha particles passed straight through the gold foil -> most of the atom is empty space
    • some alpha particles passed through but were deflected by varying amounts -> there is a positive centre to the atoms
    • some (a very few) came straight back -> the positive centre is very dense
    new evidence can replace or change a theoryhelium nucleus is alpha particleradioactivity is spontaneous, can’t really be predictedbeta is an electrongamma is an electromagnetic wavealpha particle can go few cm and is absorbed/stopped by paper, skinbeta particle can go 1 metre and is stopped by aluminium, gamma takes few cm of lead but a few feet of concrete.in a magnetic field, beta is deflected mostly, alpha is deflected slightly and opposite to beta, gamma - no deflectionwhen a beta particle leaves an atom, the neutron is converted into a proton so atomic number increases, mass number stays the samehalf life - the average time taken for half of the radioactive nuclei to decay (or count rate to reach half of its start value)gamma rays can sterilise, kill cancer cells, tracersalpha, controlling paper thickness, smoke alarmsbeta for controlling foil thicknessfission splits nucleus, generates heat in power stationfusion - joining of small nuclei- energy released, no radioactive waste products, safer, not achieved at low temperaturesfission - splitting of large atomic nuclei - energy released. radioactive waste produced, technology developed and in usegravity = force caused by nuclear radiationprotostar made of dust and gas pulled together by gravity-> main sequence star as protostar fuses hydrogen (stable as inward force of gravity balanced by outward force of radiation) -> red giant as hydrogen runs out, swells up -> star contracts and forms a white dwarf which then stops emitting light and becomes a black dwarflarger stars swell up, become red supergiant and then continue to collapse. it explodes into a supernova and the core left is a neutron star. if this is massive enough, it will become a black hole which has such a strong gravitational field that even light cannot escape it.supernova explosion distributes elements through space. heavier elements made only in the final stages of big stars e.g. ironx-rays have a very short wavelength (roughly size of an atom) cause ionisation, affect photographic film in the same way light does, absorbed by metal and boneCT scan: x ray tube connect to a CCD (charge coupled device) x rays-> light -> image displayed on a screendetailed image, softer and harder tissuesafety: lead shielding, film badgesCT scan vs X-ray machinesCT scanners: higher dose, 3D image, distinguish between different soft tissuesX rays: lower dose, 2D image, cheapersound = vibrationsvibrations per seond = frequency (Hz) low 20 Hzhigh 20,000 Hzhigher than 20,000 Hz = ultrasoundultrasound waves partially reflected when they meet different mediatime taken for reflections to reach detector measured
    each boundary distance measured
    image formed
    S = V x Ts is distance (m), v is speed (m/s), time in (s) ultrasound can break down kidney stonesultrasound is non-ionising and produces accurate images of soft tissues.convex - convergingconcave - divergingpoint where they meet is principal focusfocal length is distance between principal focus and lensconcavemagnifying glass - virtual, upright, and magnified when object is closer than principal focuslines don’t join up on right sidemagnification = image height/ object heightmagnifying glass - real, inverted, diminished when object is further than principal focus
    lines join up on right side
    convexdiminished, virtual, upright when object is closer than focal pointThe Eyelens focus light rays
    cornea is transparent, allows light in iris
    pupil: where light gets into the eye
    retina sends images to brain
    ciliary muscles help change shape
    suspensory ligaments help hold ciliary in place
    short sighted - concave lenslong sighted - convex lenshelps focus image on retinacamera - converging lens fixed focusfocus achieved by varying lens positionimage focused on film or CCDbrightness controlled by aperture and diaphragmeye- converging lens variable focusfocus achieved by contraction of ciliary muscle, image focused on retinabrightness controlled by iris and pupilimage is real, inverted and diminishedvalue of concave lens is always negative (focal length)thicker curvature decreases focal lengthhigher refractive index decreases focal lengthfor a given focal length, the greater the refractive index, the flatter the lens. the lens can be made thinner.lasers: intense and focused light (monochromatic)used with an endoscope for cauterising (sealing off) damaged blood vessels, cutting, burning, laser eye surgery
    if the line of action of the weight lies outside the base, there will be a resulting moment and the object will toppleliquids - virtually incompressiblepressure applied - transmitted equally in all directionsp = f/apressure = force/ area
    centripetal force acts towards centre, causes acceleration towards centre but direction constantly changescentripetal force increases if mass or speed increases/ radius decreasesstronger magnetic field - add iron core, more current or more coilsforce can be increased by increasing current, increasing magnetic field it can be reversed by reversing the magnetic field or reversing the current
    The motor effect is when a wire carrying a current is placed in a magnetic field and experiences a force as a result. As the current flows through the opposite sides of the coil in opposite directions, opposite forces act on each side of the coil- 1 up and 1 down which leads to the coil rotating.Insulated wires carry an alternating current in the primary coil. this produces a changing magnetic field in the secondary coil. this induces or generates an alternating potential difference or voltage across the secondary coil. and so an alternating current in the secondary coil.switch mode transformers work at higher frequencies: much lighter and smaller than transformers from mains (50Hz), useful for devices like mobile phone chargers, uses very little power
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    (Original post by Sho. Anne)
    Hi, guys! I made these notes whilst revising for unit 2 and unit 3. They cover most of the things you need to memorise for both exams so if you find it useful, just copy these down. Hope it helps acceleration - rate of change of velocity per unit per time (speeds up)deceleration - opposite of acceleration/ negative acceleration/ slows down
    velocity- speed in a given direction
    speed- distance/ time in m/s

    terminal velocity - air resistance/drag force is equal (and opposite to) the force making the object move e.g. gravity for a parachutist
    distance on velocity time graphs is the area inside the graph, underneath the line.
    work- energy transferred in joules e.g elastic potential energy on spring

    Hooke’s law - The extension of an elastic object is directly proportional to the force applied, provided the limit of proportionality is not exceeded.
    Limit of proportionality on a graph is when the line is no longer directly proportional.F= k x e

    f is force in newtons, k is n/m and extension is m.w = f x dwork is joules, force is newtons, distance is metrespower = work/timepower is watts, work is joules, time is secondskinetic energy - energy of a moving object due to its motiongravitational potential- energy of an object due to its position in a gravitational field weight- force (g, gravitational field strength) in Newtons N, downwards towards the centre of the earth.mass- kgweight- newtonsw = m x gweight in newtons, mass in kg and g is usually 10n/kg.
    P = m x vmomentum kg m/s = kg x m/s
    conservation of momentum - the total momentum before an event is equal to the total momentum after the eventmomentum also has directionthe longer the impact time, the more the impact force is reduced
    1. Seat belt reduces time taken to hit steering wheel.
    2. Air bag decreases time taken for face to hit steering wheel.
    thinking distance+braking distance = stopping distancethe faster the car travels, the longer the stopping distancetired, distraction, drinking alcohol, drugs can affect thinking distancemovement of elections (onto an insulator)gain of electrons= negativeloss of elections= positivebattery is more than one cellvoltmeter measures voltage/potential difference. ammeter measures current in amps, lamp lights up, switch controls current flow, fixed resistor lowers current, variable resistor lows current with different amounts, fuse, thermistor senses heat and e.g. adjusts heating -radiator, incubator, light dependant resistor (LDR) control resistance depending on light, light emitting diode made to make efficient lighting, diode allows current to flow only one way,resistance measured in ohmsI = Q/tcurrent in amps, charge is coulombs and the time is in seconds

    voltmeter measures potential difference
    potential difference is the work done per coulomb of charge that passes through the componentV = W/Qpotential difference in volts, work done in joules, charge in coulombs
    ohms law - current is directly proportional to the potential difference (temp is constant, fixed resistor). If you flip battery, the graph line is negative.V=IRpotential difference in volts, current in amps and resistance in ohms
    The total resistance is the sum of all the individual resistors or components.The total potential difference of the cells is the sum of the individual cells. (must be facing same way or will cancel out)The potential difference of the supply is shared between the components.The current is the same through each component.Parallel circuit: The potential difference across each component is the same.The current is different in different branches of the circuit. The total current through the whole circuit is the sum of the current through the separate components. The higher the resistance, the lower the current.LDR - negative correlation for resistance and light intensityuses: automatic lights, camera shutters, fridgesThermistor - negative correlate for temperature and resistanceuses: automatic heating systems, homes, incubatorsLED - light emitting diode - efficientcurrent and potential difference through lamp; graph is s shapeddiode only allows current in one direction, flip battery and it’ll stay at 0Temperature through current: free electrons flow through metal, hotter, atoms/ions gains energy, more vibrations, more frequent collisions, more successful collisionsElectric current -> direct current D.C (e.g. runs of battery)-> alternating current A.C (plug sockets, supplies frequency of 50 Hz and voltage of 230V in UK)the frequency of an ac supply can be determined from an oscilloscope trace using the equation f = 1/Tf is frequency in Hz, T is time in secondsperiod - time taken for 1 cycle3 core cablecopper better for conduction electricityplug has tough plastic case and it insulates the electricity, the plastic cable doesn’t break easily, cable grip/cord grip makes sure the cables don’t go out of place, fuse melts (blows) if the current is too high, brown wire (right) is live wire, blue wire is neutral wire, green and yellow wire is earth wire, and blue wire is neutral, wires are insulated with plastic cover to avoid them touching each other. 2 core cable doesn’t have earth pin as the wires are well insulated (for appliances with non-metal outer casings)earth wire is connected to metal casing of appliance in case live wire came loose and touched the casing so that the current can be directed to the earth wire and sent back into the plug, into the ground.current flows through the earth wire, has a low resistance, current goes up, blows the fuse.RCCB- residual current circuit breaker (for more dangerous things e.g. lawn mower)it is much quicker, and can be re set. wire carrying a current -> warmerfilament lamp -> gets very hot -> energy wastedCFL, compact fluorescent lamp, less heat -> more efficient -> less wasted.p = e/tpower in watts, energy transferred in joules, time in seconds.
    p=VIpower in watts, potential different in volts, current in amps
    isotope- different number of neutronsradiation or radioactivity energy comes from the nucleusgeiger-muller tube measures radioactivity in counts per minutesbackground radiation is radiation that is present naturally in low amounts. 50% from radon gas in air, also comes from food and drink, rocks, ground, buildings, cosmic rays -> outer space, medical (x rays), nuclear reactors, air travel, nuclear accidents, nuclear weapons tests.rutherford and mars den thought atoms looked like plum puddings.experiment: alpha particles (2+) fired at thin gold foil in vacuum chamber, detector
    result: some were deflected and came straight back other than going straight through.
    • most alpha particles passed straight through the gold foil -> most of the atom is empty space
    • some alpha particles passed through but were deflected by varying amounts -> there is a positive centre to the atoms
    • some (a very few) came straight back -> the positive centre is very dense
    new evidence can replace or change a theoryhelium nucleus is alpha particleradioactivity is spontaneous, can’t really be predictedbeta is an electrongamma is an electromagnetic wavealpha particle can go few cm and is absorbed/stopped by paper, skinbeta particle can go 1 metre and is stopped by aluminium, gamma takes few cm of lead but a few feet of concrete.in a magnetic field, beta is deflected mostly, alpha is deflected slightly and opposite to beta, gamma - no deflectionwhen a beta particle leaves an atom, the neutron is converted into a proton so atomic number increases, mass number stays the samehalf life - the average time taken for half of the radioactive nuclei to decay (or count rate to reach half of its start value)gamma rays can sterilise, kill cancer cells, tracersalpha, controlling paper thickness, smoke alarmsbeta for controlling foil thicknessfission splits nucleus, generates heat in power stationfusion - joining of small nuclei- energy released, no radioactive waste products, safer, not achieved at low temperaturesfission - splitting of large atomic nuclei - energy released. radioactive waste produced, technology developed and in usegravity = force caused by nuclear radiationprotostar made of dust and gas pulled together by gravity-> main sequence star as protostar fuses hydrogen (stable as inward force of gravity balanced by outward force of radiation) -> red giant as hydrogen runs out, swells up -> star contracts and forms a white dwarf which then stops emitting light and becomes a black dwarflarger stars swell up, become red supergiant and then continue to collapse. it explodes into a supernova and the core left is a neutron star. if this is massive enough, it will become a black hole which has such a strong gravitational field that even light cannot escape it.supernova explosion distributes elements through space. heavier elements made only in the final stages of big stars e.g. ironx-rays have a very short wavelength (roughly size of an atom) cause ionisation, affect photographic film in the same way light does, absorbed by metal and boneCT scan: x ray tube connect to a CCD (charge coupled device) x rays-> light -> image displayed on a screendetailed image, softer and harder tissuesafety: lead shielding, film badgesCT scan vs X-ray machinesCT scanners: higher dose, 3D image, distinguish between different soft tissuesX rays: lower dose, 2D image, cheapersound = vibrationsvibrations per seond = frequency (Hz) low 20 Hzhigh 20,000 Hzhigher than 20,000 Hz = ultrasoundultrasound waves partially reflected when they meet different mediatime taken for reflections to reach detector measured
    each boundary distance measured
    image formed
    S = V x Ts is distance (m), v is speed (m/s), time in (s) ultrasound can break down kidney stonesultrasound is non-ionising and produces accurate images of soft tissues.convex - convergingconcave - divergingpoint where they meet is principal focusfocal length is distance between principal focus and lensconcavemagnifying glass - virtual, upright, and magnified when object is closer than principal focuslines don’t join up on right sidemagnification = image height/ object heightmagnifying glass - real, inverted, diminished when object is further than principal focus
    lines join up on right side
    convexdiminished, virtual, upright when object is closer than focal pointThe Eyelens focus light rays
    cornea is transparent, allows light in iris
    pupil: where light gets into the eye
    retina sends images to brain
    ciliary muscles help change shape
    suspensory ligaments help hold ciliary in place
    short sighted - concave lenslong sighted - convex lenshelps focus image on retinacamera - converging lens fixed focusfocus achieved by varying lens positionimage focused on film or CCDbrightness controlled by aperture and diaphragmeye- converging lens variable focusfocus achieved by contraction of ciliary muscle, image focused on retinabrightness controlled by iris and pupilimage is real, inverted and diminishedvalue of concave lens is always negative (focal length)thicker curvature decreases focal lengthhigher refractive index decreases focal lengthfor a given focal length, the greater the refractive index, the flatter the lens. the lens can be made thinner.lasers: intense and focused light (monochromatic)used with an endoscope for cauterising (sealing off) damaged blood vessels, cutting, burning, laser eye surgery
    if the line of action of the weight lies outside the base, there will be a resulting moment and the object will toppleliquids - virtually incompressiblepressure applied - transmitted equally in all directionsp = f/apressure = force/ area
    centripetal force acts towards centre, causes acceleration towards centre but direction constantly changescentripetal force increases if mass or speed increases/ radius decreasesstronger magnetic field - add iron core, more current or more coilsforce can be increased by increasing current, increasing magnetic field it can be reversed by reversing the magnetic field or reversing the current
    The motor effect is when a wire carrying a current is placed in a magnetic field and experiences a force as a result. As the current flows through the opposite sides of the coil in opposite directions, opposite forces act on each side of the coil- 1 up and 1 down which leads to the coil rotating.Insulated wires carry an alternating current in the primary coil. this produces a changing magnetic field in the secondary coil. this induces or generates an alternating potential difference or voltage across the secondary coil. and so an alternating current in the secondary coil.switch mode transformers work at higher frequencies: much lighter and smaller than transformers from mains (50Hz), useful for devices like mobile phone chargers, uses very little power
    Hey just a suggestion, why dont you copy and paste this and make it as a resource in a word. Im sure it will be of much more use there and you work can be downloaded because these are great notes. Just a shame i had my physics p2 and p3 couple days ago haha.
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    Thanks for the suggestion, I was really lazy when I was posting this and didn't expect all my points to be mushed together in these big paragraphs When I have the time, I'll try and make it a document.
 
 
 

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