OCR Physics A G484 - The Newtonian World - 11th June 2015 Watch

Jackasnacks
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#1561
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#1561
(Original post by ETRC)
i only knew it was resonance because of the pencil mark lol
you had to draw a peak and label it natural frequency

then just explain resonance and say amplitude is maximum
Bollox
I did a acc-f graph
Goodbye 3 marks
Goodbye A
Goodbye uni
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randlemcmurphy
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#1562
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(Original post by MMB07)
Question 2: State in words the law used to determine your answer to i)

Mark scheme from OCR: DO NOT ALLOW NEWTON'S 2nd LAW, as in question 1 we claimed that newton was wrong
Newton wasn't wrong, the persons statement was incorrect.
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ETRC
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#1563
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#1563
(Original post by leroythelost)
What grade do you need in physics overall? I need an A and I got 34/40 for practical skills
i need an A too.

i got like 252/300 last year
if i scrape an A on this that's 72ums and i think my practical will be a C which is 40. So i'll need a very high B in g485.

If G485 is normal like other years then I can get an A comfortably but I don't think it will be normal so i am scared.
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L'Evil Fish
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#1564
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#1564
(Original post by Jackasnacks)
Bollox
I did a acc-f graph
Goodbye 3 marks
Goodbye A
Goodbye uni
Lol I did a frequency against V max graph
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ETRC
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(Original post by randlemcmurphy)
Newton wasn't wrong, the persons statement was incorrect.
who said Newton was wrong lmao
and they claim to know the mark scheme
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ibanezmatt13
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#1566
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#1566
So was it Newton's second law that we needed to state that we used in i) ?
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FummyJr
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#1567
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#1567
(Original post by MMB07)
Question 2: State in words the law used to determine your answer to i)

Mark scheme from OCR: DO NOT ALLOW NEWTON'S 2nd LAW, as in question 1 we claimed that newton was wrong
They want you to describe newtons 2nd law, they are just saying you wont get the marks for just writing the name of the law.
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rosstoal
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#1568
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#1568
(Original post by sagar448)
Was it conservation of momentum when we were working out the acceleration of the spacecraft? PLEASE TELL ME IT WAS
I put it was newtons 3rd (equal and opposite forces).
Because I found the initial acceleration of the xenon ions, the multiplied by their mass to get the force the exert in their direction.
Then due to Newtons 3rd, the spaceship experiences the same force. Then divide that same force by the mass of the spaceship to get its Acceleration

Anyone do the same?
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sagar448
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(Original post by L'Evil Fish)
Lol I did a frequency against V max graph
Dude what did you say for you know when the question asked why the temperature will take longer to rise in real?

I said the heat is lost to the surrounding since it isn't insulated or whatever didn't know second reason?
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Elcor
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#1570
(Original post by FummyJr)
They want you to describe newtons 2nd law, they are just saying you wont get the marks for just writing the name of the law.
(Original post by ibanezmatt13)
So was it Newton's second law that we needed to state that we used in i) ?
(Original post by rosstoal)
I put it was newtons 3rd (equal and opposite forces).
Because I found the initial acceleration of the xenon ions, the multiplied by their mass to get the force the exert in their direction.
Then due to Newtons 3rd, the spaceship experiences the same force. Then divide that same force by the mass of the spaceship to get its Acceleration

Anyone do the same?
I said conservation of linear momentum.
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ETRC
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(Original post by Jackasnacks)
Bollox
I did a acc-f graph
Goodbye 3 marks
Goodbye A
Goodbye uni
that's not as bad as what i did

i messed up 6 easy marks on shm questions- my brain just decided to quit
and i completely forgot about direction in momentum

i don't even know why the questions were worded so crap
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trooken
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#1572
(Original post by rosstoal)
I put it was newtons 3rd (equal and opposite forces).
Because I found the initial acceleration of the xenon ions, the multiplied by their mass to get the force the exert in their direction.
Then due to Newtons 3rd, the spaceship experiences the same force. Then divide that same force by the mass of the spaceship to get its Acceleration

Anyone do the same?
Such a confusing question. Depending on how you look at it, it could be conservation of momentum, Newton's 2nd or 3rd law
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Elcor
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(Original post by sagar448)
Dude what did you say for you know when the question asked why the temperature will take longer to rise in real?

I said the heat is lost to the surrounding since it isn't insulated or whatever didn't know second reason?
Not all the photons would be adsorbed by the titanium, some would be reflected.
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ibanezmatt13
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(Original post by rosstoal)
I put it was newtons 3rd (equal and opposite forces).
Because I found the initial acceleration of the xenon ions, the multiplied by their mass to get the force the exert in their direction.
Then due to Newtons 3rd, the spaceship experiences the same force. Then divide that same force by the mass of the spaceship to get its Acceleration

Anyone do the same?
I said that rate of change of momentum of ions remained constant, as constant exhaust velocity. And since force is rate of change of momentum, and system is closed, net force on rocket is constant.

Acceleration inversely proportional to mass. Mass decreases as ions emitted, so acceleration increases.

However didn't mention the point "total momentum is conserved" so probs lost a mark :/
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BrokenS0ulz
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you know when we had to derive keplers third law, was that basically v=2pir/T, F=mv^2/r stuff, equating them and then subbing into F =GMm/r^2?
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L'Evil Fish
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#1576
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#1576
(Original post by sagar448)
Dude what did you say for you know when the question asked why the temperature will take longer to rise in real?

I said the heat is lost to the surrounding since it isn't insulated or whatever didn't know second reason?
Lol I said photo electric effect causing emission of electrons

Didn't say about work function though, so they might assume some KE which would heat it up

But it's probably some photons reflected or something for second
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rosstoal
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(Original post by trooken)
Such a confusing question. Depending on how you look at it, it could be conservation of momentum, Newton's 2nd or 3rd law
Conservation of momentum does make sense as well, weird little exam that was
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Flux_Dubstep
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(Original post by BrokenS0ulz)
you know when we had to derive keplers third law, was that basically v=2pir/T, F=mv^2/r stuff, equating them and then subbing into F =GMm/r^2?
basically
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Elcor
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(Original post by BrokenS0ulz)
you know when we had to derive keplers third law, was that basically v=2pir/T, F=mv^2/r stuff, equating them and then subbing into F =GMm/r^2?
Yeah, and then conclude with hence T^2 is proportional to r^3 for the last mark probably.
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fatart123
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46-48 should definitely be above an A*, right? This year's paper felt harder than last year's paper tbh..
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