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    (Original post by xxariki)
    I think there was a question where it asked about temp decrease, and i think you had to find out the gradient, so you drew a triangle on the graph and it was like -9/100 and i think (probably wrong) but answer was 0.09 decrease per second
    no the change in temp was 20-13= 7, this occured over a period of 100 seconds
    7/100=0.07
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    (Original post by Mahrez)
    no the change in temp was 20-13= 7, this occured over a period of 100 seconds
    7/100=0.07
    this is correct
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    oooosh, from this mark scheme I got around 46-49. What do you all reckon the grade boundaries will be like?
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    First Question (Waves):
    -Frequency alters pitch
    -Reflected sound waves are echoes
    -When waves are diffracted they spread out
    -Most diffraction occurs when wavelength is the same as the object
    -Longitudinal waves: Oscillations are parallel to direction of travel, waves transfer energy.

    Electricity in a rural area:
    -Expensive to lay cables/put infrastructure in place (cheaper to generate electricity independent of national grid)

    Six Marker (HEP vs Wind):
    -Both renewable
    -Wind more expensive
    -Wind greater output
    -HEP continuous output (more reliable)
    -Neither release CO2
    -HEP disrupts free movement of fish
    -Wind is an eyesore

    Saucepan:
    -Inefficient as some energy is wasted as light energy, some transferred to surroundings (not 100% goes to food in pan
    -Fins: Surface area
    -Colour: Black is good emitter and absorber of Infra-red radiation

    Electromagnetic Waves:
    -Same speed through a vacuum
    -Not within visible spectrum (so are invisible to naked eye) ?
    -Able to diffract/refract/reflect
    -Use of Micro: Phones, Satellite Communications
    -Use of Infra-red: Optical Fibres (for internet), Remote Controls (has appeared on mark schemes before)
    -Cosmic Microwave Background Radiation
    -Provides evidence for The Big Bang Theory/Big bang theory is only theory that can explain its presence

    Solar Cell Question:
    -Scientists strive for low cost because.. (according to table) cheaper to get two 10% efficient solar cells (1m2) than one 20% efficient solar cell - works out at a quarter of the cost to get two 10% (£10) compared to one 20% (£40)

    Nuclear Power Advantages:
    -Cheaper per kWh of electricity (table)
    -No CO2 released ?
    -Less fuel required for great amounts of energy so supply is not an issue ?

    Nuclear Power Disadvantages:
    -Produces radioactive waste (which must be disposed of properly to prevent harm)
    -Fuel source (uranium/plutonium) is non-renewable
    -High cost to decommission/Takes a long time to decommission

    USB Heater - Factors:
    -Surface area of mug in contact with heater
    -Temp. difference between mug and heater ?

    USB Heater - Conduction:
    -Particles at base of mug gain energy, vibrate
    -Pass on extra kinetic energy to neighbouring particles, carries on through the solid to transfer heat

    Convection 4 marker:
    -Heated particles gain (kinetic and thermal) energy
    -Increased movement
    -Particles move apart
    -That area of liquid becomes less dense, rises
    -Cycle repeats

    How science works question:
    -Thermometer has a smaller resolution (goes up in degrees while the data logger combo did 0.1 increments)
    -Data logger continuously records information, not at intervals ?
    -Removes human error

    Why does the average temperature of a liquid go down as it evaporates?
    -Particles gain energy when heated
    -When heated enough particles rise up and leave the liquid, evaporating and taking energy with them
    -As energy is no longer in the liquid the average particle energy decreases so the temperature also decreases

    Calculations:
    -340m/s
    -0.07 degrees/second
    -0.48kW
    -6.4 ?
    -78 degrees
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    (Original post by Mahrez)
    no the change in temp was 20-13= 7, this occured over a period of 100 seconds
    7/100=0.07
    I got this too.
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    For the control variable it had to be linked with the rate of evaporation (That is what the experiment was about). I put the airflow has to remain the same. This ensures that all three liquids are not affected by factors that can influence the rate of evaporation.
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    (Original post by dhruvap)
    For the control variable it had to be linked with the rate of evaporation (That is what the experiment was about). I put the airflow has to remain the same. This ensures that all three liquids are not affected by factors that can influence the rate of evaporation.
    surface area of container/beaker
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    (Original post by Mahrez)
    surface area of container/beaker
    Yes that could be another factor.
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    (Original post by ihatehannah)
    14) control variable for the investigation measuring rate of evaporation (1) : same beaker or same type of beaker, same position in the room., same thermometer
    For this one i put same time period of investigation and same intervals between checking temperature, is that correct?
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    (Original post by TruthfulHoax)
    First Question (Waves):
    -Frequency alters pitch
    -Reflected sound waves are echoes
    -When waves are diffracted they spread out
    -Most diffraction occurs when wavelength is the same as the object
    -Longitudinal waves: Oscillations are parallel to direction of travel, waves transfer energy.

    Electricity in a rural area:
    -Expensive to lay cables/put infrastructure in place (cheaper to generate electricity independent of national grid)

    Six Marker (HEP vs Wind):
    -Both renewable
    -Wind more expensive
    -Wind greater output
    -HEP continuous output (more reliable)
    -Neither release CO2
    -HEP disrupts free movement of fish
    -Wind is an eyesore

    Saucepan:
    -Inefficient as some energy is wasted as light energy, some transferred to surroundings (not 100% goes to food in pan
    -Fins: Surface area
    -Colour: Black is good emitter and absorber of Infra-red radiation

    Electromagnetic Waves:
    -Same speed through a vacuum
    -Not within visible spectrum (so are invisible to naked eye) ?
    -Able to diffract/refract/reflect
    -Use of Micro: Phones, Satellite Communications
    -Use of Infra-red: Optical Fibres (for internet), Remote Controls (has appeared on mark schemes before)
    -Cosmic Microwave Background Radiation
    -Provides evidence for The Big Bang Theory/Big bang theory is only theory that can explain its presence

    Solar Cell Question:
    -Scientists strive for low cost because.. (according to table) cheaper to get two 10% efficient solar cells (1m2) than one 20% efficient solar cell - works out at a quarter of the cost to get two 10% (£10) compared to one 20% (£40)

    Nuclear Power Advantages:
    -Cheaper per kWh of electricity (table)
    -No CO2 released ?
    -Less fuel required for great amounts of energy so supply is not an issue ?

    Nuclear Power Disadvantages:
    -Produces radioactive waste (which must be disposed of properly to prevent harm)
    -Fuel source (uranium/plutonium) is non-renewable
    -High cost to decommission/Takes a long time to decommission

    USB Heater - Factors:
    -Surface area of mug in contact with heater
    -Temp. difference between mug and heater ?

    USB Heater - Conduction:
    -Particles at base of mug gain energy, vibrate
    -Pass on extra kinetic energy to neighbouring particles, carries on through the solid to transfer heat

    Convection 4 marker:
    -Heated particles gain (kinetic and thermal) energy
    -Increased movement
    -Particles move apart
    -That area of liquid becomes less dense, rises
    -Cycle repeats

    How science works question:
    -Thermometer has a smaller resolution (goes up in degrees while the data logger combo did 0.1 increments)
    -Data logger continuously records information, not at intervals ?
    -Removes human error

    Why does the average temperature of a liquid go down as it evaporates?
    -Particles gain energy when heated
    -When heated enough particles rise up and leave the liquid, evaporating and taking energy with them
    -As energy is no longer in the liquid the average particle energy decreases so the temperature also decreases

    Calculations:
    -340m/s
    -0.07 degrees/second
    -0.48kW
    -6.4 ?
    -78 degrees
    The comparision one is to get same efficnetcy as A you need twice of C which cost 4 times less
    Buying 8 solar cells of C has a greater output than 1 of A
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    (Original post by Mahrez)
    The comparision one is to get same efficnetcy as A you need twice of C which cost 4 times less
    Buying 8 solar cells of C has a greater output than 1 of A
    A has the 20% efficiency, C has 10% - what you've said is on the post just in different words. Yours is much clearer thank you.
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    (Original post by Habina786xx)
    Sameee I put that!!!

    Posted from TSR Mobile
    don't they have different wavelengths and frequenices though?
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    I still don't get the increasing VOLUME question and how it affects the rate of evaporation. Faster or slower?
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    (Original post by TruthfulHoax)
    A has the 20% efficiency, C has 10% - what you've said is on the post just in different words. Yours is much clearer thank you.
    No problem
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    (Original post by dhruvap)
    I still don't get the increasing VOLUME question and how it affects the rate of evaporation. Faster or slower?
    Decreasing volume quicker rate of evapouration
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    [QUOTE=CaSama9;65166409]
    (Original post by ihatehannah)
    1. Frequency ( 1)

    what question was the 78 degrees one again?
    46200J energy transferred, starting temperature of water is 100 degrees, speceific heat capacity of water is 4200, work out final temperature of the liquid in the beaker.
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    (Original post by Mahrez)
    Decreasing volume quicker rate of evapouration
    Surely if you decrease volume, there is less surface area, so there is a slower rate of evaporation.
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    For the bat question I didn't put echoes I put sonar/ultrasound.
    For the similarities between radio and microwaves I put that they both have low frequency and long wavelengths (I didn't put that they were the same)
    For the question about longitudinal sound waves I put that they were mechanical so needed atoms present to travel.
    I know for a fact that these are 'correct' but I'm not sure whether they're specific enough to receive marks or are what the question was looking for. Any ideas?
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    (Original post by SunnyBoys)
    Surely if you decrease volume, there is less surface area, so there is a slower rate of evaporation.
    That's is what I wrote.
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    (Original post by SunnyBoys)
    Surely if you decrease volume, there is less surface area, so there is a slower rate of evaporation.
    There's a lower density so more particles will have the energy to evaporate I think
 
 
 
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