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AQA Physics GCSE P2 & P3 [OFFICIAL THREAD]

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Reply 400
I bet unit 2 will bring up car safety, regarding seat belts and crumple zones. Does anyone have an explanation of what they do?
is it bad i only started revising for the physics exam when i came home at 3?
A 3 pin core has a neutral wire (blue), an earth wire (green and yellow) and a neutral wire (brown). A three pin core cable isboften used in non insulated appliances that have metal cases instead of plastic cases for example a kettle or a toaster. A three pin core cable is much safer than a two pin core cable as any excess electricity is more likely to be taken straight to the earth wire and away from the person to avoid electrical shock.
Original post by maxjackson5
I'm sure you'll get it! Good luck!


I hope so, good luck to you too! If only we got results straight after doing each exam, then we'd know what to aim for :frown:
Original post by Pra99
Elements heavier than iron are formed in a supernova not as heavy as iron thanks a lot by the way


Your very welcome!

No, we're both correct. The various nuclear reactions that occur (fusion) form elements as heavy as Iron. It's when these nuclear reactions "explode" as the Supernova contracts that elements heavier than iron are formed and ejected into the universe. Creating new stars and planets.

I think aslong as we mention that elements heavier and as heavy as iron are produced from nuclear reactions taking place, we'll get the marks! :smile:
Original post by Amy Hickman
is it bad i only started revising for the physics exam when i came home at 3?


Not really, I did the same, you'll do well as long as you understand the stuff. Good luck; you'll be fine!
Original post by metrize
Not really, I did the same, you'll do well as long as you understand the stuff. Good luck; you'll be fine!


Haha, thanks! you too xx
Have you finished revising now?
Reply 407
What do you say about impact forces? All I understand is that increasing the time will decrease the force?
Original post by Nai18
I bet unit 2 will bring up car safety, regarding seat belts and crumple zones. Does anyone have an explanation of what they do?


Types of features include
1. Seat Belts
2. Airbags
3. Crumple Zones
4. Side Impact Bars

Just remember that all these safety features INCREASE the time in which momentum acts on people inside the car.

As in a car crash, the people inside experience a huge amount of kinetic energy converted into other forms of energy in a very short period of time. Which can be fatal!

Increasing the time in which these passengers come to stop from the force of momentum just reduces the force acting on them. Making it safer!

Hope this helps!

Do you want explanations on the different safety features and what they specially do?
On the spec for P2 it says "Candidates should be able to explain resistancechange in terms of ions and electrons."
but I dont know what it is ... Can someone please explain it to me please!!! Thanks and good luck... for me physics is my worst science anways :frown:
Everyone's talking about how they really want a*s and I'm just here going to look forward to a B if I can manage that...

Tbh CGP really is a livesaver though
Seat Belts increase the time over which the change in momentum occurs, lessening the force on the chest. Also absorbed some kinetic energy.
Crumple zones convert kinetic energy into other forms of energy as it crumples and increase the time taken for the change in momentum again lessening the force.
Side impact bars direct energy away from the passengers to the crumple zones decreasing the the force on passengers.
Airbags increase the time taken over which the change in momentum happens, decreasing the force on the body. They also provide something soft to fall against.
Reply 412
Original post by turquoisecat
Please explain critical angle when angle of incidence and refraction is given... I'm a little confused!!!


Posted from TSR Mobile


I don't know if someone has replied but basically, you need to work out the refractive index of the material if you have been given the angle of incidence and angle of refraction with the equation 'refractive index (n) = sin(angle of incidence)/sin(angle of refraction) or n= sin(i)/sin(r)'

Once you know the refractive index of the material, you can measure the critical angle of it by using 'critical angle(c) = sin^-1(1/refractive index) or c = sin^-1(1/n)

I hope this helps...it's quite long winded so sorry but if you don't get it then feel free to ask again- it's helping me revise too! 😄
good luck m8tys
Original post by Pra99
Thanks a lot. Hydrogen isn't produced by the way😃


Hydrogen is produced by Nuclear Fusion of Helium Nuclei.

What other form of fuel are you proposing that our sun uses to stay "stable" in its main sequence period? :tongue:
Reply 415
Original post by t.thompson22
Types of features include
1. Seat Belts
2. Airbags
3. Crumple Zones
4. Side Impact Bars

Just remember that all these safety features INCREASE the time in which momentum acts on people inside the car.

As in a car crash, the people inside experience a huge amount of kinetic energy converted into other forms of energy in a very short period of time. Which can be fatal!

Increasing the time in which these passengers come to stop from the force of momentum just reduces the force acting on them. Making it safer!

Hope this helps!

Do you want explanations on the different safety features and what they specially do?


Sure thing :smile:
Original post by ladyrailly
Everyone's talking about how they really want a*s and I'm just here going to look forward to a B if I can manage that...

Tbh CGP really is a livesaver though


I'm exactly the same! I need a B to do A Level biology and chemistry :colondollar:
Reply 417
Original post by MVEMJSUNP
On the spec for P2 it says "Candidates should be able to explain resistancechange in terms of ions and electrons."
but I dont know what it is ... Can someone please explain it to me please!!! Thanks and good luck... for me physics is my worst science anways :frown:


Is this talking about electrical circuits?
If it is then for a filament bulb at least, the resistance of the bulb increases as the current increases. This is because an increase in current causes the wire in the bulb to heat up, therefore increases the kinetic energy of the ions in the metal wire. As the kinetic energy is greater and the metal ions vibrate more, the electrons (current) cannot pass through the wire as easily as there as more collisions between these electrons and the ions in the wire, hence the resistance increases as the current increases.

Does this make sense? Don't worry about physics, just try your best!! 💪
Original post by t.thompson22
Nervous, but ready!
If it's as easy as chemistry was then I'll be happy. What are your predictions for tomorrow?


I have not really thought about it; hopefully stars will come up, there was a lot on static electricity in the 2014 paper so I doubt we will be seeing much of that, what do you think?
Original post by t.thompson22
I'm exactly the same! I need a B to do A Level biology and chemistry :colondollar:


Nice! Our college requires that but I'm not doing A levels :biggrin:. Tbh I'll be quite happy for a B in physics & ecstatic for an A. There's no way in hell I'm getting an A* and I can admit that quite proudly. In fact there's no way I'm getting A*s in any of the Sciences but I don't like science so :tongue:

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