AQA Physics PHYA5 - 28th June 2016 [Exam Discussion Thread]

Original post by nyxxllis

example

I believe you're meant to know the average binding energy per nucleon for iron because it's the highest value. It is about 9MeV. I know if they ask you to draw the graph you need to show the max value at around 9 MeV for a value of A around 50.

Reply 405

nnblccz

7

Anybody else find they repeatedly miss out on marks because of how the mark scheme is phrased? I basically write the right thing every time but somehow manage to not get the marks, so annoying

Reply 406

Original post by twallien

I believe you're meant to know the average binding energy per nucleon for iron because it's the highest value. It is about 9MeV. I know if they ask you to draw the graph you need to show the max value at around 9 MeV for a value of A around 50.

Yeah, i'm aware it's 8.89 MeV but it specifically asks you to calculate it. In the markscheme it seems to include a value for the mass of the isotope to something like 4dp. I can't believe that we're meant to know that by heart?

Reply 407

HandsomeRakk

Original post by Whizbox

Any turning points 6 marker predictions? Motivation for this exam is at a new low, just one more

Know that feeling bro :bebored:

Reply 408

Craig David

Original post by nyxxllis

Yeah, i'm aware it's 8.89 MeV but it specifically asks you to calculate it. In the markscheme it seems to include a value for the mass of the isotope to something like 4dp. I can't believe that we're meant to know that by heart?

You do 56 times u to find it.
Then working it out as usual by finding the ones for individual protons and neutrons. You then subtract. and finish up.

Reply 409

Original post by nyxxllis

Yeah, i'm aware it's 8.89 MeV but it specifically asks you to calculate it. In the markscheme it seems to include a value for the mass of the isotope to something like 4dp. I can't believe that we're meant to know that by heart?

The AQA formula sheet provides the rest mass for protons and neutrons so just finding number of protons and the number of neutrons and multiplying them by thier respective rest masses

Reply 410

Craig David

Original post by twallien

The AQA formula sheet provides the rest mass for protons and neutrons so just finding number of protons and the number of neutrons and multiplying them by thier respective rest masses

What you said doesn't make sense?

Reply 411

Original post by Craig David

You do 56 times u to find it.
Then working it out as usual by finding the ones for individual protons and neutrons. You then subtract. and finish up.

I may be wrong but this would surely just give the total binding energy of the atom?

Reply 412

Original post by Craig David

What you said doesn't make sense?

This would completely rid any mass defect, the individual components of the atom have more mass than the actual atom so doing this there would be no way to calculate the mass defect because there wouldn't be any?

Reply 413

Original post by Craig David

What you said doesn't make sense?

Can you post the mark scheme answer?

Reply 414

Windowswind123

Original post by 124375

In question 1bii of June 2014 why is the mass of the neutrons ignored??? I don't get it!

Binding energy is the amount of energy required to separate a nucleus into its constituent nucleons. No energy is required to separate a neutron because it wasn't part of the nucleus in the first place.
I think anyway..

Reply 415

Craig David

Original post by nyxxllis

This would completely rid any mass defect, the individual components of the atom have more mass than the actual atom so doing this there would be no way to calculate the mass defect because there wouldn't be any?

Exactly. You then divide by the amount of nucleons.

What he said would give you zero. Doesn't make much sense. You are back to the starting point.

Reply 416

Original post by twallien

Can you post the mark scheme answer?

I want to know where the 55.93493 figure comes from, i can do the rest. This appears to be the measured value for the mass of the atom but isn't stated in the question anywhere?

Reply 417

Questioner1234

7

Original post by Windowswind123

Binding energy is the amount of energy required to separate a nucleus into its constituent nucleons. No energy is required to separate a neutron because it wasn't part of the nucleus in the first place.
I think anyway..

I got stuck on that question too and I though that since neutrons have rest energy wouldn't that be included? Otherwise where does that energy come from

Posted from TSR Mobile

Reply 418