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# OCR 21st Century Science Physics P4 P5 P6 *Unofficial Mark Scheme 2016* watch

1. 1 (a) (i) 22N (1 mark)
(ii) 11 J (2 marks)
(iii) conservation of energy is the idea that energy is never created or destroyed, only transferred or converted. It applies to Roy because his kinetic energy was converted into waste heat energy through conservation. (2 marks)
(b) 5.48 to 2dp - working below
35nx1.5m = 52.5j
G.D.P = energy transferred, so 53.5 = 1/2x3.5kgx(velocity)^2
Rearrange to get 30 = velocity ^2
Velocity = 5.48m/s (3 marks)

2 (a) (i) around 12.5 seconds (1 mark)
(ii) 6.5 m/s (2 marks)
(b) The top tick box, "speed increases, then decreases until the lorry becomes stationary" (1 mark)
(c) Reaction (1 mark)
(d) Because the weight of the lorry was caused by the Earth's gravity, not by the road. (2 marks)

3 Car crash seat belt and air bag (6 marks)
-in a collision, the car comes to a stop very suddenly
-change in momentum = resultant force x time for which the force acts, therefore as the change in momentum is constant and can't be changed, and as the time is very small, the resultant force is very large
-therefore passengers get injured because there is a large force acting on them, which causes a lot of pressure on the body in a short space of time.
-seat belts are slightly elastic so they stretch slightly. This means that, in a crash, the time taken for the body to stop moving is increased, so the force on the chest is reduced.
-air bags are released. Passengers' heads collide with these instead of the windscreen or dashboard, both of which are hard surfaces. As airbags are soft, they increase the amount of time taken for the passengers' heads to stop moving, so force to the head and neck is reduced.
-by reducing the amount of force, the pressure which the body undergoes is reduced, and so the risk and severity of injury are reduced significantly.

4 Explain how a transformer induces a voltage across the secondary coil: There is an alternating voltage on the primary coil which leads to an alternating current in the coil. This alternating current produces an alternating magnetic field in the iron core which induces an alternating voltage in the secondary coil. (3 marks)

5 (a) Electromagnetic induction (1 mark)
(b) You could have said a few for this one: putting the opposite pole of the magnet in (ie south instead of north), spinning the magnet, taking the magnet out (1 mark)
(c) Because it increases the size of the voltage (and therefore current) in the wire. (1 mark)

6 (a) Graph C (the one that looks like a sin graph) (1 mark)
(b) Iron (1 mark)

7 Resistance in parallel wires (6 marks)
-the results show a negative correlation, as the number of wires increases, the resistance in the wires decreases.
- increasing the number of pathways means the current gets shared, and therefore it is less in each wire
- this therefore reduces the resistance
- she could improve by using a wider range and more intervals to help get a clear trend
- she could use a different set of wires (possibly different length or width wires as both of these factors affect resistance)

8 If I remember rightly these were the calculation ones.
(a) (i) 5 Ω (1 mark)
(ii) 0.5 V (1 mark)
(b) (i) 1.5 V (1 mark)
(ii) 0.2 A (1 mark)

9 (a) Source C because:
- gamma radiation so it leaves the body quickly
- half life of around 1 hour so the exposure time is quite short and damage is limited (3 marks)
(b) Alpha radiation can't be detected by the badge because it is stopped by all 3 materials so can't pass through any of them. (1 mark)
(c) line drawn from beta to second box down
line drawn from gamma to top box (2 marks - 1 mark for each line)
(d) 4,500,000,000 J (or 4.5x10⁹ J) (2 marks)
(e) Eve, Ben (2 marks, 1 for each correct)
(f) He thinks that the perceived risk is higher than the statistical/calculated risk because he has no control over the plant, he doesn't know how it works and so might seem dangerous to him, past nuclear disasters, media and can't see radiation. (3 marks)

-irradiation means being exposed to ionising radiation without coming into direct contact with the source.
-irradiation is used on vegetables to sterilise them - ionising gamma radiation kills all the microbes on the food so it's safe to eat and has a long shelf life (no bacteria exist to grow as mould on it for a while)
-because irradiation doesn't involve contact with the source, the ionising effects stop as soon as the vegetables are removed from the source
-Donna's concerns are unfounded because the food is not radioactive, therefore she cannot become contaminated by eating the vegetables as she is not ingesting radiation

? Somewhere in the paper there was the question "how is high level radioactive waste dealt with?" But I don't know where it was: it is stored in glass and steel canisters in water for up to 50 years to cool, before being moved to more permanent storage (burial). (2 marks)

Feel free to add things, or change something you believe is wrong as I am in no way saying that my answers are definitely correct!

I thought I'd make a mark scheme because there have been an annoying lack of them for this board - and I know they're highly sought after. So enjoy!
2. My answers for the P456 (the ones I can remember for the short answers anyway):• 22N• 11J• 5m/s (pretty sure is wrong)• Iron core• Eve• Ben• 5 Ohms• 1.5V• 3V• 0.2A• 45,000,000,000 J• Magnetic induction• The Wavey looking voltage thing• C, for the half-life, as gamma less ionising in the body• Something about perceived risk is over exaggerated by the calculated risk• Alpha is not strong enough to go through • Beta- second last box• Gamma- last boxThat’s all I remember, but itd be nice to compare what you guys got, to see how badly I actually did lol
3. What do you think the grade boundaries are going to be??????
4. I think the first 2are wron as you do 5*4= 20
And for the second one I got 10j
5. I personally thought it was quite a bit harder than last years but easier in comparison to others so I would predict 39-42 for an A* but not sure
6. (Original post by 11207ymir)
I think the first 2are wron as you do 5*4= 20
And for the second one I got 10j
Nah you had to add the weight of the box too, which was 2N...ultimately making 22N, therefore leading b) to be 11 J as u half it
7. 1)
B: I think it was 5.48 to 2dp
35nx1.5m = 52.5j
G.D.P = energy transferred, so
53.5 = 1/2x3.5kgx(velocity)^2
Rearrange to get 30 = velocity ^2
Velocity = 5.48m/s
9 and beyond
A)Source C, because it has to be gamma as alpha gets absorbed by the skin. C was closer to a half life of one hour. (2000/2 = 1000 which is close to 980)
B) Alpha can't be detected as it gets absorbed by all materials on the badge.
C) beta went to the second one, gamma to the first one.
D) energy produced by reactor is 4,500,000,000j
E) can't remember
F) some man thinks that the perceived risk is higher than the statistical risk because he has no control over the plant, he doesn't know how it works and so might seem dangerous to him, past nuclear disasters, media and can't see radiation.
8. (Original post by Unknown123321)
1)
B: I think it was 5.48 to 2dp
35nx1.5m = 52.5j
G.D.P = energy transferred, so
53.5 = 1/2x3.5kgx(velocity)^2
Rearrange to get 30 = velocity ^2
Velocity = 5.48m/s
9 and beyond
A: Source C, because it has to be gamma as alpha gets absorbed by the skin. C was closer to a half life of one hour. (2000/2 = 1000 which is close to 980)
B) Alpha can't be detected as it gets absorbed by all materials on the badge.
C) beta went to the second one, gamma to the first one.
D) energy produced by reactor is 4,500,000,000j
E) can't remember
F) some man thinks that the perceived risk is higher than the statistical risk because he has no control over the plant, he doesn't know how it works and so might seem dangerous to him, past nuclear disasters, media and can't see radiation.
Can you explain the beta and gamma question with the lines please?
9. The induction one, there is a alternating voltage on the primary coil which leads to an alternating current in the coil. This alternating current produces an alternating magnetic field in the iron core which induces an alternating voltage in the secondary coil.
10. (Original post by bekahhiggins)
Can you explain the beta and gamma question with the lines please?
Well if the box becomes shaded it means that it has been exposed to radiation ( this was written somewhere on the alpha question before the beta and gamma question)
So gamma can only pass though card and aluminium and so the card and aluminium box is shaded, which was the top one. Beta only goes though card so the card box is the only one shaded, which was the second one.
11. Thank you all, will add these!
12. (Original post by NiamhM1801)
Thank you all, will add these!
There was also that tick box question, I think it was the first one but not sure.
13. (Original post by Unknown123321)
Well if the box becomes shaded it means that it has been exposed to radiation ( this was written somewhere on the alpha question before the beta and gamma question)
So gamma can only pass though card and aluminium and so the card and aluminium box is shaded, which was the top one. Beta only goes though card so the card box is the only one shaded, which was the second one.
Thanks! I messed that one up big time as I thought for some reason beta went though aluminium and gamma went through lead.

A* - 44
A - 37
B - 31
C - 24

This is just going off of the fact that last years were medium (A* was 41, B was 34, etc), and a lot of people were saying this test went well so I'm predicting grade boundaries will be roughly 3 marks higher than last year, although I can't really remember if I've done the paper from last year so it may have been easier or harder than this years.

A* - 44
A - 37
B - 31
C - 24

This is just going off of the fact that last years were medium (A* was 41, B was 34, etc), and a lot of people were saying this test went well so I'm predicting grade boundaries will be roughly 3 marks higher than last year, although I can't really remember if I've done the paper from last year so it may have been easier or harder than this years.
Ye, the 6 markers were pretty generous in this test.
16. (Original post by Unknown123321)
There was also that tick box question, I think it was the first one but not sure.
Ah yes I know which one you mean
17. Does anyone know where the question with Ben and Eve was?
18. Thanks! Finally somebody does ocr 21st century science!

A* - 44
A - 37
B - 31
C - 24

This is just going off of the fact that last years were medium (A* was 41, B was 34, etc), and a lot of people were saying this test went well so I'm predicting grade boundaries will be roughly 3 marks higher than last year, although I can't really remember if I've done the paper from last year so it may have been easier or harder than this years
I think that's abit high I think an A will be about 34/35
20. (Original post by Miss Studious)
Thanks! Finally somebody does ocr 21st century science!
You're welcome! And I know right, I swear it's the least done exam board - I was getting sick of the lack of mark schemes so made my own

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