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AQA GCSE - Unit 3 (P3,B3,C3) New specification papers.

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Reply 1220
Avatar for a123a
a123a
14
Hi guys, I'm trying to find information on the social and economical advantages and disadvantages of alcohols, carboxylic acids and esters. If anyone could help me on this I would very much appreciate it. Thanks in advance!
Original post by a123a
Hi guys, I'm trying to find information on the social and economical advantages and disadvantages of alcohols, carboxylic acids and esters. If anyone could help me on this I would very much appreciate it. Thanks in advance!


You don't need to know much about the economic and social advantages and disadvantages of alcohols, carboxylic acids and esters, and any question on this subject will likely provide you with some information to interpret. However, some important points to remember are:

- Alcohols, carboxylic acids and esters can be used in many ways in foods, drinks and as fuels

- Alcoholic drinks and solvents can be abused which can lead to health and social problems

- Biofuels offer an alternative to fossil fuels and help with problems of diminishing resources and climate change

- However, some of the crops used for the production of biofuels require the use of agricultural land which could be used to grow food
So what we know is that this exam is out of 60. But does anybody have a rough idea of what an A* will be ? Obviously I'm not expecting a definitive answer as nobody knows but is there a trend from maybe Unit 1 ?

If somebody could estimate what 91 UMS, 95 UMS & 99 UMS you are a star !
91 about 46
95 about 50
99 about 54
please note that they are only guesses :P
revision game anyoneee?
Original post by sneakbo2
revision game anyoneee?

sure, you start :wink:
Original post by Captain Anonymous
please note that they are only guesses :P

Will we be doing the first sitting of these exams? If so, they may be lower :eek:
hmm okay

B3 - 4 problems caused by Deforestation
Original post by sneakbo2
hmm okay

B3 - 4 problems caused by Deforestation

1) Disruption of habitats, less biodiversity
2) Increase of C02 levels in atmosphere
3)Increasing levels of methane
4) Less carbon dioxide taken in :biggrin:

How does a hydraulics system work?
Original post by lolface32
1) Disruption of habitats, less biodiversity
2) Increase of C02 levels in atmosphere
3)Increasing levels of methane
4) Less carbon dioxide taken in :biggrin:

How does a hydraulics system work?


Ahh can't remember this. Pressure is transmitted equally in all parts of the liquid. In the case of pistons, one piston has a higher surface area than the other, although the pressure transmitted is the same in both pistons. Using the formula P=F/A we can see that pistons are useful as they are a efficient way of increasing force, because as the area increases, so does the force exerted. :confused:

Give 3 problems associated with having an artificial heart.
Original post by sneakbo2
Ahh can't remember this. Pressure is transmitted equally in all parts of the liquid. In the case of pistons, one piston has a higher surface area than the other, although the pressure transmitted is the same in both pistons. Using the formula P=F/A we can see that pistons are useful as they are a efficient way of increasing force, because as the area increases, so does the force exerted. :confused:

Give 3 problems associated with having an artificial heart.

Yep, that is perfect! :biggrin:

Artificial hearts may have risk of infection during surgery
Will need to be constantly supplied with battery power
Valves in the artificial hearts can easily be worn (something like this)
Original post by Captain Anonymous
91 about 46
95 about 50
99 about 54


Too low compared to the boundaries we had
Original post by NightStrider
Too low compared to the boundaries we had


What would you say the boundaries be ? Again, this is purely guess work
Original post by Midnight1811
What would you say the boundaries be ? Again, this is purely guess work



I personally think the boundaries will be high. Everyone knows their stuff now, the retakes for module 1s were all low possibly because alot of d/c grade students who probably got a free retake from their school were retaking which pulled it down. The module 3s are also the easiest in my opinion and there isnt that much to learn, therefore lots of people are gonna be scoring very high. Just look at the C2 boundaries, it was the same thing there. Thats why instead of worrying about grade boundaries, get 60/60 raw marks.
Original post by Midnight1811
What would you say the boundaries be ? Again, this is purely guess work


50s across the board
50's across the board are ridiculous, I would say around mid-high 40's
Reply 1237
Avatar for CD223
CD223
10
Could somebody please explain to me all the details we need to know about switch mode transformers for P3? Its a small topic that we really rushed in class and its been bugging me ever since...


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Original post by CD223
Could somebody please explain to me all the details we need to know about switch mode transformers for P3? Its a small topic that we really rushed in class and its been bugging me ever since...


Posted from TSR Mobile


Switch transformers work at a higher frequency (around 50kHz to around 200kHz) than normal transformers do, which means that they can be smaller and lighter (since the higher the frequency the more energy they carry). it also makes them useful for chargers and power supplies for laptops/computer.

As well as this, switch transformers are also more efficient because when no load (like your phone, for example) is plugged in, then the switch transformer (in this case, your charger) uses little energy, so they save on energy costs.
Reply 1239
Avatar for CD223
CD223
10
Original post by Graviton-Pulse
Switch transformers work at a higher frequency (around 50kHz to around 200kHz) than normal transformers do, which means that they can be smaller and lighter (since the higher the frequency the more energy they carry). it also makes them useful for chargers and power supplies for laptops/computer.

As well as this, switch transformers are also more efficient because when no load (like your phone, for example) is plugged in, then the switch transformer (in this case, your charger) uses little energy, so they save on energy costs.


Thank you so much! I swear I've learnt more from that overview than in lesson haha.


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