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# OCR PHYSICS B G494~ 11th June 2015 AM ~ A2 Physics watch

1. (Original post by urz13)
For the one where you had to show that Tp = a constant if relationship was true, I said it wasnt true as they were all different (none were exactly the same). Will I be penalized for this?
I said they were different, i tested it out with much higher values of T and lower values of p that still fitted with the pattern in the table, and it was definitely not constant, but i don't know what they wanted :-(
2. (Original post by rapunzelsa)
i got 3.86 as well
Ok cool, looks like the comments on here earlier about 3.96 were mistaken.

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3. (Original post by Greating)
This is what a friend and I think are acceptable answers, though there is some uncertainty in some of the longer explanation questions.

The relationship wasn't true, they weren't all the same value

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4. For the measuring of the decay constant question, could you put measure number of decays of a nucleus in a certain time and do decay constant equals the number of decays / time (in seconds) ?
5. I did that too! Iliterally always make those questions up as I go along and just hope for the best ahah!
6. (Original post by Greating)
This is what a friend and I think are acceptable answers, though there is some uncertainty in some of the longer explanation questions.

Damn I screwed up the pV=constant one. I worked it out then proceeded to divide p by V instead of multiplying! Asides from that, what I wrote what correct - the 'equation' they gave you was not valid because the values calculated were not constant (for me at least).

How many marks was that question? 3/4? Hopefully I'll only lose 1 or 2 marks for that

Nice markscheme anyway 😊

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7. (Original post by asdfghi)
For the measuring of the decay constant question, could you put measure number of decays of a nucleus in a certain time and do decay constant equals the number of decays / time (in seconds) ?
I did something similar, but you'd need to divide by N too, since dN/dt = -decay constant x N.

The comments on here and in that unofficial mark scheme about drawing the decay curve and measuring gradient etc seem more logical though, not sure we'd get the mark.

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8. (Original post by rapunzelsa)
I said they were different, i tested it out with much higher values of T and lower values of p that still fitted with the pattern in the table, and it was definitely not constant, but i don't know what they wanted :-(
Who knows - we might get the benefit of the doubt
9. (Original post by asdfghi)
For the measuring of the decay constant question, could you put measure number of decays of a nucleus in a certain time and do decay constant equals the number of decays / time (in seconds) ?
That would give you activity though wouldn't it?

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10. (Original post by Mutleybm1996)
The relationship wasn't true, they weren't all the same value

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I got numbers around the value 352 for each one so I said that it was constant, as the +-1 difference was negligible
11. (Original post by MasterOfTheSwag)
I got numbers around the value 352 for each one so I said that it was constant, as the +-1 difference was negligible
That came up in one of the past papers
they were +-1 or 2 out too and I said they were constant, the mark scheme said otherwise, hence I said they're not proportional
12. (Original post by Robbo54)
Ok for the natural log questions I divided the two values so you cancel the two constants, and re-arranged to get Epsilon, anyone do a similar method to this?
I equated the constants and that was how I managed to get the answer people have got.
13. (Original post by Iridann)
I equated the constants and that was how I managed to get the answer people have got.
Did you get the values as constant relationship or not?

I know I made some mistakes, but I don't think it's enough to cost me an A
Well, I hope not any way!
14. (Original post by rapunzelsa)
I said they were different, i tested it out with much higher values of T and lower values of p that still fitted with the pattern in the table, and it was definitely not constant, but i don't know what they wanted :-(
I just wrote that it does work with the equation because they were all like 351, 352, 353 so they were all 350 to (2.s.f.) and the differences are just due to experiments always have error! or something like that anyway
but they probably accept it if you say it doesnt work with the equation as long as you justified why!!
15. (Original post by Greating)
This is what a friend and I think are acceptable answers, though there is some uncertainty in some of the longer explanation questions.

Thanks for that!

I think i got most calculations right. The explanations i think could've gone better but overall made me feel a little more confident!
16. (Original post by nair39)
Only a mark lost for your conclusion I reckon. As long as your calculations were right you'd get those marks.

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I wouldn't give up hope of getting all those marks, often the markscheme accepts both as long as you explain why you came to your conclusion and it is valid. That being said i also said the relationship was true
17. Was the graph p against V

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18. (Original post by malachirp)
I wouldn't give up hope of getting all those marks, often the markscheme accepts both as long as you explain why you came to your conclusion and it is valid. That being said i also said the relationship was true
you rounded to 2sf right, the data was to 3sf though
19. (Original post by saycell_96)
Was the graph p against V

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P vs T
straight line through origin

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