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

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Original post by bafid
definitely ln10 because it was just 10/1=e^...


Oops I did 10-1
The rest was right though
How many marks lost?


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(edited 8 years ago)
Reply 201
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bafid
1
Original post by Mutleybm1996
Someone here did it using sim.equations and got 2.8 too


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Shame its wrong though, the answer is ln10*k/(1/300-1/400) type it into a calculator = 3.9*10^-20 - there is no other answer, youve made a calculation error somewhere
Original post by bafid
Shame its wrong though, the answer is ln10*k/(1/300-1/400) type it into a calculator = 3.9*10^-20 - there is no other answer, youve made a calculation error somewhere


If I did ln(10-1) but the rest correctly how many marks lost??


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Original post by Mutleybm1996
If I did ln(10-1) but the rest correctly how many marks lost??


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Probably only 1 because you've gone about it the right way
Reply 204
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bafid
1
Original post by Mutleybm1996
If I did ln(10-1) but the rest correctly how many marks lost??


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1 if they dock you just the accuracy mark, but possibly 2 if they dock a working one as well for not dividing
Original post by bafid
1 if they dock you just the accuracy mark, but possibly 2 if they dock a working one as well for not dividing


How was that questions only worth two marks - there was so much work to do.
Original post by Robbo54
How was that questions only worth two marks - there was so much work to do.


Probably because it was that hard a lot of people may not of been able to do it. So if they can't they don't lose to many marks
Reply 207
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nair39
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I agree, normally that kind of question is worth 3 or 4 marks. I can imagine it'd be particularly difficult if you didn't do A-level Maths, although I'm guessing most people who do Physics do Maths too...

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This is what a friend and I think are acceptable answers, though there is some uncertainty in some of the longer explanation questions.

Our answers are attached.
g494.pdf29.8KB
Original post by Robbo54
How was that questions only worth two marks - there was so much work to do.


There is actually a quicker alternative way to work it out I think, I've done a similar question in a past paper.

G494 June 2012 Q11c)

And the mark scheme gave:


And yeah I forgot that method so I just done it the long way, using the additional space on the back.
Kinetic energy is transferred to elastic potential energy in the deformed satellite. But you probably get the mark for just saying kinetic energy is transferred to different forms of energy and then giving an example (heat or sound).
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?


Yes
Original post by nair39
For the logs question, I did, my answer was 3.86 * 10^-20.

Anyone get this, rather than 3.96? I've checked it again just now, so I'm sure it's right unless I made a silly mistake.

my answer was epsilon = ln10 / [(1/(300*k))-(1/(400*k))] which gives 3.86 * 10^-20


i got 3.86 as well
Reply 213
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urz13
8
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?
Reply 214
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nair39
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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?


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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The last question is going to be a horror to mark because there are so many practical ways of doing it and every one can be done in either direction (i.e. pushing the frequency above 2Hz or below 0.2Hz.
Reply 216
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urz13
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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.

Our answers are attached.


If those are right (which they seem to be) I've dropped between 7 and 10 marks I'd say, which is massively frustrating after averaging about 55/60 on past papers. Hopefully grade boundaries for an A* are around the 48 mark.
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 :-(
Reply 218
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nair39
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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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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.

Our answers are attached.


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


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