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AQA Physics GCSE Unit 1 2017 unofficial mark scheme watch

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    Question 1:
    Type of wave? Transverse (1 mark)
    Frequency = 4.6x10^14 (3 marks)
    Bottom box - 10^-15 - 10^4 (1 mark)

    Question 2:
    Design A is better because: larger surface area of pipe; pipe coloured black instead of white, black is a good absorber of IR; pipe is metal which is a good conductor, while Design B is plastic which is a poor conductor; surface of Design A white and shiny so it does not absorb IR, reflects it instead, while surface of Design B is dark and matt meaning it absorbs heat instead of pipe (6 marks)

    Question 3:
    Two factors affecting output voltage? Surface area of blades; power of hairdryer/wind speed from hairdryer; distance of hairdryer from turbine (2 marks)
    Plot values on graph (2 marks)
    Type of measurement error? Random error (I think, not sure on this one) (1 mark)
    Two conclusions from graph? Need more than one blade to generate electricity; voltage increases with number of blades (2 marks)
    Two considerations when manufacturing turbines? Cost and ease of manufacture; ease of maintenance (2 marks)

    Question 4:
    What effect? Doppler effect (1 mark)
    Which car was moving towards? Car A because the frequency increased (2 marks)
    Which car was moving fastest? Car C because the difference in frequency was greatest (2 marks)

    Question 5:
    Solid biofuel? Wood; peat; plants/animal waste may gain mark (1 mark)
    Change in temperature? 380°C (3 marks)
    Why is oven designed with:
    White surface? Bad emitter so heat from oven is lost more slowly
    Curved surface? Help convection currents form maybe? (thanks sweatyasian for this one). Decreased surface area so less heat loss.
    High specific capacity? Slow to lose heat, takes a lot of energy to heat
    Low U value? Material is good insulator, decrease heat loss (4 marks)

    Question 6:
    Calculate input power: 6.25W (2 marks)
    Number of hours to charge: 4 hours. 1.6 hours is incorrect as you used the total input power for the power, not the useful output power which was 2.5W. An answer of 1.6 with correct working gains either 1 or 2 marks (3 marks)
    Why less than 2.5W output? Energy from sun is unreliable as it's not always sunny? Unsure on this one (2 marks)
    Why longer to charge if turned on? Phone turned on would constantly use energy so requires more energy to charge (2 marks)

    Question 7:
    Transformer J = step up transformer, increases voltage decreases current to minimise energy loss and increase efficiency
    Transformer K = decrease voltage increase current to make voltage safe to use in the home (4 marks)
    How is energy stored in pumped storage power station? During periods of low demand water is pumped up to high level reservoir, when electricity is cheaper, gains gravitational potential energy; during periods of high demand water is allowed to flow down to low level reservoir to generate electricity and meet demand (4 marks)
    Why is a pumped storage power station used to meet demand? Water pumped up to high level reservoir when demand and cost is low. Quick start up time so generates electricity very quickly when demand is high (2 marks)

    Question 8:
    Convection current in drink? Drink particles near chiller lose energy and move closer together, drink becomes less dense. More dense drink sinks and less dense, warmer drink at bottom rises, forming convection current (3 marks)
    How does the rate of energy transfer change as drink cools? Decreases because difference in temperature decreases (2 marks)
    Why does condensation form on bottle? Water vapour particles in air lose energy when they hit the cool bottle and change from a gas to a liquid (condense). Water forms on the bottle (3 marks)

    Thanks everyone for contributions, I've been updating it based on what you all think even if I haven't replied
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    For the charging time I got 6 hours instead of 4. I did 36/6.25 giving me 5.76 which I then rounded up to 6. Can somebody confirm if I'll get marks for this?
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    What would the grade boundaries be like. I thought it was harder than this years biology and chemistry, though not too hard.
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    (Original post by Badboi787)
    For the charging time I got 6 hours instead of 4. I did 36/6.25 giving me 5.76 which I then rounded up to 6. Can somebody confirm if I'll get marks for this? I also said Dopplar effect and not Doppler will I get marks for that too? For the hair dryer and blades question I said the power of the hair dryer and quality of wires since if the wires are low quality this can effect readings?

    I also said that the voltage increases dramatically from one blade to two and from two to four blades the voltage increases by 0.05v.

    For the construction of wind turbines I put down location - needs to be in a windy area, and length of blades for more surface area.
    See for that question i got 5760 seconds, which converts to 1.6 hours. Though I think I'd get maybe 1 or 2 out of 3 for that. I think you should get at least 1 mark if you have writted the equation correctly.
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    (Original post by Badboi787)
    For the charging time I got 6 hours instead of 4. I did 36/6.25 giving me 5.76 which I then rounded up to 6. Can somebody confirm if I'll get marks for this? I also said Dopplar effect and not Doppler will I get marks for that too? For the hair dryer and blades question I said the power of the hair dryer and quality of wires since if the wires are low quality this can effect readings?

    I also said that the voltage increases dramatically from one blade to two and from two to four blades the voltage increases by 0.05v.

    For the construction of wind turbines I put down location - needs to be in a windy area, and length of blades for more surface area.
    I got 5.76 too,, comes to 5hours 45mins 36 seconds but everyone is posting that it was 4 hours????? Confused lmao
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    What was the type of measurement error? I initially put human but changed it to random error since the markschemes usually say human error is insufficient.
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    (Original post by Badboi787)
    For the charging time I got 6 hours instead of 4. I did 36/6.25 giving me 5.76 which I then rounded up to 6. Can somebody confirm if I'll get marks for this? I also said Dopplar effect and not Doppler will I get marks for that too? For the hair dryer and blades question I said the power of the hair dryer and quality of wires since if the wires are low quality this can effect readings?
    Unfortunately, I don't think you will get a mark for that. You used the input power into the solar panel, not the power input into the battery. Also, the 36 was kilojoules, not joules.

    You had to convert 36KJ to 36000J. Then divide 36000 by 2.5 J/s (the same as watts). That gets you 14400s. So it takes 14400 seconds to charge. Convert that into minutes by dividing by 60, and then into hours by dividing by 60 again.
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    Is cow dung or animal dung enough for a solid biofuel?
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    Crap omg Im so stupid I wrote 5760 and it was hours????😂😂👏🏾👏
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