OCR 21st Century 16th June P4 P5 P6 unofficial mark scheme

Unofficial mark scheme please help so we can fill out all the answers
These answers have been verified by many but could be wrong

Predicted Boundaries
Full UMS - 43
A* - 37
A - 30
B - 23
C - 18

Forces question(3)
Arrow up for reaction
Arrow going to the left for friction
Arrow going to the right as push

Resultant force(2)
Yes it is 0 as speed is constant, forces equal no acceleration

KE mass of ball(2)
50g

Reasons why ke isnt transferred: (2)
Heat energy lost
Sound energy lost

Momentum(2)
2kg m/s

Circle time(1)
0.5ms

Keeping velocity same and decreasing force(2)
Change in momentum = force x time so increasing the time the force is acting on the ball will make up for the lower force

6 marker
Draw the graph
Talk about velocity and acceleration at different points
Definition of displacement

Current question(2)
150A

Circuit drawing(2)
Voltmeter parallel to the motor
Ammeter anywhere else

Lamp and current question(2)
Current in a parallel circuit is added up so it is 2A + 2A and not 4A when the lamp is broke

Electric cars(2)
Advantage - No air pollution from burning fuel in engines, co2 emissions, global warming
Disadvantage - electricity being made causes pollution at the power station

Terminal and electrons(1)
To the positive terminal

Transformer(3)
Alternating current in primary constantly changes direction of magnetic field in core
Electromagnetic induction provides alternating voltage in secondary
How turns affect the step up or step down conversion

Transformed voltage circle(1)
4v

6 marker
- Calculation of resistances(it was in mega amps)
- Proving it was negatively correlated using figures
- Description of a thermistor
- Proving there was correlation for the second one
- explanation of why current is higher(less resistance = less collisions between ions and electron)

Background radiation(1)
Always present radiation

Affect of distance to meter(1)
Counts increase
Half life no change

Irradiation and Contamination(3)
-Exposure to source only for the time you are near it e,g, in an area of lots of radon gas
-Physical and direct contact with source e.g. touching radioactive granite
-Irradiation is less harmful, contamination more harmful e.g. Damaging internal organs

Dan and Lucy(3)
-100 to 50 shows dan is correct
-Varying rates for the half lives after that show that background radiation is having an impact and lucy is correct
-calculations for the half lives

Half lives(1)
2

Nuclear equation(2)
222 on top and 52 on bottom

Similarity and Difference between 2 radon isotopes(2)
1. Both have same number of proton
2. Have different number of neutrons

6 marker
- 2000msv is very high to ensure killing of living cells in the tumour
- Description of ionisation
- The radiation is directed carefully at the tumour so cancers dont form elsewhere
- irradiation of other patients and doctors avoided through use of concrete blocks during process and keeping the patient separate to others

(edited 6 years ago)

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Reply 1

kilner

I think for the second question you were meant to mention terminal velocity?

Reply 2

Sidwhit

You know for question1 part two I put there not as gravity is acting upon it and that why the ball is falling

Reply 3

Pm18ftw

Original post by kilner

I think for the second question you were meant to mention terminal velocity?

I dont think so im pretty sure u talked about the resultant force being at 0 as speed wasnt increasing so it was constant and that meant all forces had to be equal to maintain constant speed

Reply 4

DD2508

Original post by Pm18ftw

Unofficial mark scheme please help so we can fill out all the answers
These answers have been verified by many but could be wrong

Forces question(3)
Arrow up for reaction
Arrow going to the left for friction
Arrow going to the right as push

Resultant force(2)
Yes it is 0 as speed is constant, forces equal no acceleration

KE mass of ball(2)
50g

Reasons why ke isnt transferred: (2)
Heat energy lost
Air resistance

Momentum(2)
2kg m/s

Circle time(1)
0.5ms

6 marker
Draw the graph
Talk about velocity and acceleration at different points
Definition of displacement

Current question(2)
150A

Help me update them pls

I think it should be energy lost as heat, and energy lost as sound?

Reply 5

Pm18ftw

Original post by DD2508

I think it should be energy lost as heat, and energy lost as sound?

Heat is definitely correct but as for air resistance thats what people were saying at my school im not sure

Reply 6

WAWAW

Original post by DD2508

I think it should be energy lost as heat, and energy lost as sound?

That's what I put

Reply 7

Pm18ftw

Original post by WAWAW

That's what I put

Ok i will change that now then u better be right lol

Reply 8

CandidateZero

There was a question about the advantages and disadvantages of electric cars (2 marks)

There was a question about electromagnetic induction in a transformer (3 marks)

There was a question about the transformed voltage - 4 Volts. (1 mark)

Question about contamination and radiation with regards to granite and radon gas. (3 marks)

Reply 9

Pm18ftw

Original post by CandidateZero

Thanks! Will update some more answers now

Reply 10

ktb786

For the second question, it wasn't an interaction pair, Chris is wrong. Because the two forces are acting on the same object. This came up last year, come on!!!!

Reply 11

kilner

6 marker on the gamma knife, that really got me.

1 mark on how putting the radioactive material nearer the machine would affect the recording and half life

Reply 12

CandidateZero

6 mark question about conclusions made from data about thermistors - a negative correlation between resistance and temperature and a positive correlation between current and temperature (thus the first statement was incorrect)

6 mark question identifying risks of cancer tumour treatment from data. Delivers a dose of 2000 mS, yet the dose leading to fatality is 5000 mS; detail about mutations and radiation AND ways in which to reduce the risk: using lead blocks to stop gamma rays being absorbed by unaffected parts of body and using only the necessary dose.

Reply 13

CandidateZero

Question about placing radiative material closer to detector - counts would change and so would half life (I believe) (1 mark)

Reply 14

ktb786

6 Mark P6:
Use the gamma with a short half life so the radiation quickly disappears
Make sure that gloves are used so contamination is prevented
Ensure thick clothing is there to also prevent contamination
Keep the patient separate from others so the radiation does not spread and irradiate others

Reply 15

WAWAW

Original post by CandidateZero

Question about placing radiative material closer to detector - counts would change and so would half life (I believe) (1 mark)

I thought the counts would change but the half life wouldn't? Could be wrong tho

Reply 16

CandidateZero

Original post by WAWAW

I thought the counts would change but the half life wouldn't? Could be wrong tho

Possibly. I can't remember exactly what I put - this answer was what I was told.

Reply 17

kilner

Original post by WAWAW

I thought the counts would change but the half life wouldn't? Could be wrong tho

Same here- the half life is the time for the sample to half so surely wouldn't be affected by distance to the recorder?

Reply 18

WAWAW

There was a tick box about what flows and in what direction in a current

Reply 19

CandidateZero

The grade boundaries for additional Physics exams rarely exceed 40 marks for the A* benchmark. Therefore, I'd say given that it was only slightly easier than last year's paper, we can expect the A* boundary to be 38-42 marks.