2016 AQA Physics Unit 1 - Unofficial Mark scheme

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

no the change in temp was 20-13= 7, this occured over a period of 100 seconds
7/100=0.07

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

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

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

Sameee I put that!!!

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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.

I still don't get the increasing VOLUME question and how it affects the rate of evaporation. Faster or slower?

1. Frequency ( 1)

what question was the 78 degrees one again?

Decreasing volume quicker rate of evapouration

Surely if you decrease volume, there is less surface area, so there is a slower rate of evaporation.

Surely if you decrease volume, there is less surface area, so there is a slower rate of evaporation.