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OCR Physics A G485 - Frontiers of Physics - 18th June 2015

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The grade boundaries for an A have been as high as 81 for this paper :frown:
Original post by L'Evil Fish
Btw binding energy is the

*minimum* amount of energy to separate all the nucleons in a nucleus

I am in bed rn, going to have breakfast, make a cuppa, and do June 13 with some music, this is the type of revision I enjoy


Sounds exciting hf.

iirc thats the fun question with the tension/electric force.

How have you learnt all the boring essay questions, the ones that lack physics.

Just rote learning or something else.
Original post by EmmaBxoxo
Sounds exciting hf.

iirc thats the fun question with the tension/electric force.

How have you learnt all the boring essay questions, the ones that lack physics.

Just rote learning or something else.


Yeah just did it, not even an hour :woo:

Didn't have to rote learn, it all made sense, and my answers line up with the mark scheme thankfully, so I'm glad I didn't have to sit and learn them all

But after marking them, your answers get closer and closer to mark scheme
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Original post by kate8
But the mass of separate nucleons is greater than the mass of combined nucleons?


yeah the mass of the seperated nucleons is greater than when they join as combined nucleons and change in mass is released as energy because of e=mc^2

i
Original post by jcwh97
The rate of expansion never reaches 0 because that implies the universe will stop expanding and reach the finite limit, but the theory states the universe never reaches this limit. The rate of expansion is asymptotic.

No I know that it never actually reaches zero, that's why I said tend to zero, it's hard to explain in words without a graph but I like the way you have explained it I will use that!
Original post by ETRC
yeah the mass of the seperated nucleons is greater than when they join as combined nucleons and change in mass is released as energy because of e=mc^2

i

binding energy is greater than zero starting at nucleon number 2 right?
When a capacitor is charged, disconnected from the power supply and then connected to a second capacitor, the potential difference across each halves. Makes sense I guess.

However, also, the total energy stored between the capacitors (often?) decreases. This is due to heat losses in the wires that connect them. Also makes sense...

...but, why does the equation 1/2CV^2 show this effect, when it seemingly hasn't been factored into the equation?

For example - air resistance can alter the theoretical acceleration of a body - but this isn't shown by F = ma.

Have a look in the OCR textbook on Page 166 if you don't get what I'm on about... Worked Example 2 :smile:
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Original post by Chung224
binding energy is greater than zero starting at nucleon number 2 right?


yeah because hydrogen is first element and has a proton and neutron so when they join to form hydrogen energy is released.

i have a feeling they might ask us when is binding energy per nucleon greater than 0 for what element or how many nucleons.
Original post by actanide
you have gravitational, because nucleons have mass. This force is pretty much negligble.

you have electrostatic that repulses positive protons because theyre positive.

and then you have the strong nuclear force which has a very short range. It holds the nucleons together and at the same time it prevents them from being squashed


can you remember which paper this came up in,
thanks anyone
Original post by L'Evil Fish
Yeah just did it, not even an hour :woo:

Didn't have to rote learn, it all made sense, and my answers line up with the mark scheme thankfully, so I'm glad I didn't have to sit and learn them all

But after marking them, your answers get closer and closer to mark scheme


Nice :smile:

That's good then.

Is this your last exam?
don't understand jan 2013 8bii). If the star has a larger surface area, surely the intensity of the emitted radiation would decrease since intensity = power/area?
Original post by kate8
Hi, can someone please explain binding energy and how it links to E=mc2. Don't really understand it at all!


binding energy = minimum amount of energy required to separate nucleons from the nucleus.
binding energy = mc^2.
individual nucleons have more mass than the original nucleus (mass defect) as energy was needed to separate the nucleons (binding energy) this energy converted into mass. (my logic)
Original post by EmmaBxoxo
Nice :smile:

That's good then.

Is this your last exam?


Just marked it, lost marks on silly things :lol:

Like leaving Hubble in s^-1 even though units were in something else

All is well woooo
Original post by L'Evil Fish
Just marked it, lost marks on silly things :lol:

Like leaving Hubble in s^-1 even though units were in something else

All is well woooo


haha, how many times has age of the universe came up!

Not suprised if it comes up tomorrow.
Original post by gothmog827
don't understand jan 2013 8bii). If the star has a larger surface area, surely the intensity of the emitted radiation would decrease since intensity = power/area?

the power being outputted by a red giant is colossal because of its large surface area
Original post by gothmog827
don't understand jan 2013 8bii). If the star has a larger surface area, surely the intensity of the emitted radiation would decrease since intensity = power/area?


Its just the fact that you have such a huge surface area, the amount of the radiation coming from it will increase even when its cooler. Nothing to do with power or intensity, just the size of the star
What do we have to know about the Doppler effect? The spec says qualitative explanations. Does this mean we don't have to know any equations? Thanks.
Original post by SkilledNChilled
What do we have to know about the Doppler effect? The spec says qualitative explanations. Does this mean we don't have to know any equations? Thanks.


we do need to know the equation.
Original post by nothepreacher
we do need to know the equation.


What equation? There are two different ones given in the book and it is not said which one to use or to remember it. Also what does it mean by the "car acts as a mirror". How can an image of something move by "2x" if the car moves by "x"? Makes zero sense to me.
Original post by SkilledNChilled
What equation? There are two different ones given in the book and it is not said which one to use or to remember it. Also what does it mean by the "car acts as a mirror". How can an image of something move by "2x" if the car moves by "x"? Makes zero sense to me.


the equation of (change of lambda/lab lambda) = (velocity/speed of light) one, and probably the v=(lambda * frequency) one from last year

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