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# AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread] watch

1. (Original post by Questioner1234)
Anyone know statistically which is most common in the multiple choice A,B,C or D, in case of having to guess?
This is the number of appearances of A, B, C and D for the last 9 papers

A: 56
B: 56
C: 56
D: 57

So from the past papers D is 0.44444444% more likely than any other answer so insignificant
2. Why does everyone do it the hard way
3. If you move a magnet through a coil of wire at a constant speed will the emf induced be 0 or be a constant value above 0?
4. (Original post by Charlie1523)
If you move a magnet through a coil of wire at a constant speed will the emf induced be 0 or be a constant value above 0?
it will induce an emf as there is a change in magnetic flux due to the magnet moving
in most questions speed is always constant so max emf is the same value throughout
emf=0 when their is NO movement
5. (Original post by Charlie1523)
If you move a magnet through a coil of wire at a constant speed will the emf induced be 0 or be a constant value above 0?
constant value
6. (Original post by Music With Rocks)
How do we know whether to use Fleming's left or right hand rule in a question?

Right hand rule is for generators isn't it?
left hand for equations F=BQv and F=BIL
Right hand for the direction of current in a coil
7. Does anyone recall using the right hand rule in any of the past papers
8. http://filestore.aqa.org.uk/subjects...W-MS-JAN13.PDF
In 2ai? Why do they do -6370 and not -7370?
9. (Original post by cmrol)
This is the number of appearances of A, B, C and D for the last 9 papers

A: 56
B: 56
C: 56
D: 57

So from the past papers D is 0.44444444% more likely than any other answer so insignificant
Something that might be helpful; over the past 9 papers (not including 2015 because I didn't have the mark scheme) no option has ever been right more than 7 times in the same paper
10. (Original post by cmrol)
Something that might be helpful; over the past 9 papers (not including 2015 because I didn't have the mark scheme) no option has ever been right more than 7 times in the same paper
June 2015 also follows this pattern (A 7, B 6, C 6, D 6).
11. (Original post by Ayaz789)
http://filestore.aqa.org.uk/subjects...W-MS-JAN13.PDF
In 2ai? Why do they do -6370 and not -7370?
42 200KM is the radius of the satellite from the centre of the earth. They are taking away 6.37*10^6 because this is the radius of the earth, giving the height above the earth.

The 7370Km figure is from a different, low orbit, satellite.
12. (Original post by micycle)
42 200KM is the radius of the satellite from the centre of the earth. They are taking away 6.37*10^6 because this is the radius of the earth, giving the height above the earth.

The 7370Km figure is from a different, low orbit, satellite.
But they take away 6,37*10^3?
13. (Original post by micycle)
42 200KM is the radius of the satellite from the centre of the earth. They are taking away 6.37*10^6 because this is the radius of the earth, giving the height above the earth.

The 7370Km figure is from a different, low orbit, satellite.
Dw its because its in Km , im just acting dumb
14. (Original post by micycle)
Anyone?

15. https://60abffc9b401b1c0936e01291c15...%20Physics.pdf

Can anyone explain q10 and q11 here.

For 11, Ep = GmM/r, so if r is getting smaller Ep would get bigger, since its inversely proportional. But its asking for the incorrect answer, since it is not A, then A must be right; but it makes no sense how, can anyone explain this?

I guess q10 as B, but have no idea why it is.

Thanks
16. (Original post by boyyo)
https://60abffc9b401b1c0936e01291c15...%20Physics.pdf

Can anyone explain q10 and q11 here.

For 11, Ep = GmM/r, so if r is getting smaller Ep would get bigger, since its inversely proportional. But its asking for the incorrect answer, since it is not A, then A must be right; but it makes no sense how, can anyone explain this?

I guess q10 as B, but have no idea why it is.

Thanks
for 11, you are using the wrong formula. when it asks about potential energy, think graviatational potential. If you jump, you gain gravitational potential, and as you fall you loose that graviational potential. The field lines point towards, for example, the centre of the earth. thus A is right. B and C are correct, so D is wrong. and it you look at the formula, g=GM/r^2 so it is actually inversely proportional to r^2.

10 is B as the pattern for damping is B and D, and light damping does not reduce the amplitude greatly, thus the amplitude is higher than D, so B.
17. Can anyone help with this? thanks http://filestore.aqa.org.uk/subjects...1-QP-JUN13.PDF
Question 19

Two satellites P and Q, of equal mass, orbit the Earth at radii R and 2R respectively.Which one of the following statements is correct?
A P has less kinetic energy and more potential energy than Q.
B P has less kinetic energy and less potential energy than Q.
C P has more kinetic energy and less potential energy than Q.
D P has more kinetic energy and more potential energy than Q.

My issue here is surely Q, travelling at a higher radius than P, would have a higher speed and hence more kinetic energy? But that's wrong according to the answer. Also, doesn't the potential decrease at increased distance, or are we including because its minus???
19. (Original post by ssel17)

Two satellites P and Q, of equal mass, orbit the Earth at radii R and 2R respectively.Which one of the following statements is correct?
A P has less kinetic energy and more potential energy than Q.
B P has less kinetic energy and less potential energy than Q.
C P has more kinetic energy and less potential energy than Q.
D P has more kinetic energy and more potential energy than Q.

My issue here is surely Q, travelling at a higher radius than P, would have a higher speed and hence more kinetic energy? But that's wrong according to the answer. Also, doesn't the potential decrease at increased distance, or are we including because its minus???
No, the satellites which orbit closer have higher speed and therefore kinetic energy

Think of it as the further out the satellites are, the higher their potential energy and therefore the lower their kinetic energy
20. Okay so pretty good with mosr areas now....the only thing im struggling wkth is potentials.

For both grav and electric potentials do two masses or charges interact with each other.....for instance is you were 500km above earths surface and there was no moon your potenital=x ....now if the moon is there what happens to the potential at the same spot?

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