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AQA Physics PHYA5 - Thursday 18th June 2015 [Exam Discussion Thread]

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Original post by Qwerty1996
These are the answers i got for nuclear, they;re not all right but if we edit the post we can make a markscheme
1a) Alpha radiation (1)
1b) 0.05m and 1m (2)
1bii) Gamma radiation obeys inverse square law (1)
1c) Inhaling the source. Outside the body it cannot penetrate through skin but inside it can damage cell membranes and cause mutation (2)

2ai) Electrostatic repulsion (1)
2aii) Charge on isotope nucleus remains the same so the effect is the same (1)
2b) 1.4 x 10^-15
2bii) 5 x 10^-15
2c) 1.4 x 10^17 kg/m^3

3a) added on a beta minus decay and an antineutrino
3b) 3.4 x 10^-6
3bii) 2.4 x 10^17
3ci) 2 or 3 fast moving neutrons are released when a uranium nucleus decays. These go onto be absorbed by other uranium nuclei causing further fission and so a chain reaction.
3cii) Slows the fast moving nuclei by giving KE to water atoms so they can be absorbed for fission
3cii) The walls absorb radiation causing excitation of atoms in the wall and thus radiation is given off

4a) Takes 130J of energy to raise the temp of 1kg of lead by 1K without change of state
4b) 47000J
4c) 6 marker

5a) Molecules move in constant rapid motion, all collisions are elastic

Thats all the ones i wrote down


And for 2c) it said show that it's approximately 1.4 but I got 1.3
For anyone doing applied, did you get 125J for the work done on gas with the P-V diagram? 67.5 +57.5?
Original post by Qwerty1996
These are the answers i got for nuclear, they;re not all right but if we edit the post we can make a markscheme
1a) Alpha radiation (1)
1b) 0.05m and 1m (2)
1bii) Gamma radiation obeys inverse square law (1)
1c) Inhaling the source. Outside the body it cannot penetrate through skin but inside it can damage cell membranes and cause mutation (2)

2ai) Electrostatic repulsion (1)
2aii) Charge on isotope nucleus remains the same so the effect is the same (1)
2b) 1.4 x 10^-15
2bii) 5 x 10^-15
2c) 1.4 x 10^17 kg/m^3

3a) added on a beta minus decay and an antineutrino
3b) 3.4 x 10^-6
3bii) 2.4 x 10^17
3ci) 2 or 3 fast moving neutrons are released when a uranium nucleus decays. These go onto be absorbed by other uranium nuclei causing further fission and so a chain reaction.
3cii) Slows the fast moving nuclei by giving KE to water atoms so they can be absorbed for fission
3cii) The walls absorb radiation causing excitation of atoms in the wall and thus radiation is given off

4a) Takes 130J of energy to raise the temp of 1kg of lead by 1K without change of state
4b) 47000J
4c) 6 marker

5a) Molecules move in constant rapid motion, all collisions are elastic

Thats all the ones i wrote down



For 3b) I got .3 instead of .4
For 3bii) 8.2*10-11 😱😱
Reply 3603
Original post by Qwerty1996
These are the answers i got for nuclear, they;re not all right but if we edit the post we can make a markscheme
1a) Alpha radiation (1)
1b) 0.05m and 1m (2)
1bii) Gamma radiation obeys inverse square law (1)
1c) Inhaling the source. Outside the body it cannot penetrate through skin but inside it can damage cell membranes and cause mutation (2)

2ai) Electrostatic repulsion (1)
2aii) Charge on isotope nucleus remains the same so the effect is the same (1)
2b) 1.4 x 10^-15
2bii) 5 x 10^-15
2c) 1.4 x 10^17 kg/m^3

3a) added on a beta minus decay and an antineutrino
3b) 3.4 x 10^-6
3bii) 2.4 x 10^17
3ci) 2 or 3 fast moving neutrons are released when a uranium nucleus decays. These go onto be absorbed by other uranium nuclei causing further fission and so a chain reaction.
3cii) Slows the fast moving nuclei by giving KE to water atoms so they can be absorbed for fission
3cii) The walls absorb radiation causing excitation of atoms in the wall and thus radiation is given off

4a) Takes 130J of energy to raise the temp of 1kg of lead by 1K without change of state
4b) 47000J
4c) 6 marker

5a) Molecules move in constant rapid motion, all collisions are elastic

Thats all the ones i wrote down


I can't quite remember all my answers but those all look pretty much the same as what I put.
Any MS for Astrophysics (2A) ?
Original post by bwr19
I can't quite remember all my answers but those all look pretty much the same as what I put.


For the ones where it said "show that it is close to this", for the follow up questions where it required use of that value, do you use the value you calculated or do you use the one that they said in the question?
Original post by ImNormal
For the ones where it said "show that it is close to this", for the follow up questions where it required use of that value, do you use the value you calculated or do you use the one that they said in the question?


I think they usually allow either?
Original post by Qwerty1996
These are the answers i got for nuclear, they;re not all right but if we edit the post we can make a markscheme
1a) Alpha radiation (1)
1b) 0.05m and 1m (2)
1bii) Gamma radiation obeys inverse square law (1)
1c) Inhaling the source. Outside the body it cannot penetrate through skin but inside it can damage cell membranes and cause mutation (2)

2ai) Electrostatic repulsion (1)
2aii) Charge on isotope nucleus remains the same so the effect is the same (1)
2b) 1.4 x 10^-15
2bii) 5 x 10^-15
2c) 1.4 x 10^17 kg/m^3

3a) added on a beta minus decay and an antineutrino
3b) 3.4 x 10^-6
3bii) 2.4 x 10^17
3ci) 2 or 3 fast moving neutrons are released when a uranium nucleus decays. These go onto be absorbed by other uranium nuclei causing further fission and so a chain reaction.
3cii) Slows the fast moving nuclei by giving KE to water atoms so they can be absorbed for fission
3cii) The walls absorb radiation causing excitation of atoms in the wall and thus radiation is given off

4a) Takes 130J of energy to raise the temp of 1kg of lead by 1K without change of state
4b) 47000J
4c) 6 marker

5a) Molecules move in constant rapid motion, all collisions are elastic

Thats all the ones i wrote down

2)a)ii) was two marks I think too

I'm sure for the one about the core walls, in past exams you've had to mention that they absorb the neutrons-I put that and that it absorbs the other energy
(edited 8 years ago)
does anyone remember the answers for medical physics?
Original post by Sam.B57
2)a)ii) was two marks I think too

I'm sure for the one about the core walls, in past exams you've had to mention that they absorb the neutrons-I put that and that it absorbs the other energy


Nope, it was only 1 mark cus I remembering thinking about how much I should write.
Original post by ImNormal
Nope, it was only 1 mark cus I remembering thinking about how much I should write.


I thought it was two because I remember making two points
Original post by Qwerty1996
These are the answers i got for nuclear, they;re not all right but if we edit the post we can make a markscheme
1a) Alpha radiation (1)
1b) 0.05m and 1m (2)
1bii) Gamma radiation obeys inverse square law (1)
1c) Inhaling the source. Outside the body it cannot penetrate through skin but inside it can damage cell membranes and cause mutation (2)

2ai) Electrostatic repulsion (1)
2aii) Charge on isotope nucleus remains the same so the effect is the same (1)
2b) 1.4 x 10^-15
2bii) 5 x 10^-15
2c) 1.4 x 10^17 kg/m^3

3a) added on a beta minus decay and an antineutrino
3b) 3.4 x 10^-6
3bii) 2.4 x 10^17
3ci) 2 or 3 fast moving neutrons are released when a uranium nucleus decays. These go onto be absorbed by other uranium nuclei causing further fission and so a chain reaction.
3cii) Slows the fast moving nuclei by giving KE to water atoms so they can be absorbed for fission
3cii) The walls absorb radiation causing excitation of atoms in the wall and thus radiation is given off

4a) Takes 130J of energy to raise the temp of 1kg of lead by 1K without change of state
4b) 47000J
4c) 6 marker

5a) Molecules move in constant rapid motion, all collisions are elastic

Thats all the ones i wrote down


Thanks for that. Do people have any different answers? Let's make a mark scheme for section A at least. And can someone confirm if the marks are all correct?

For 2a I got electromagnetic, but I think that would get marks as well
What was 2b and 2bii? I remember getting 1.3 as well but I used the value I worked out not the one they give.
Original post by ubisoft
Thanks for that. Do people have any different answers? Let's make a mark scheme for section A at least. And can someone confirm if the marks are all correct?

For 2a I got electromagnetic, but I think that would get marks as well
What was 2b and 2bii? I remember getting 1.3 as well but I used the value I worked out not the one they give.


2bi and 2bii were both show that questions I think: 2bi show that r0is roughly 1.4*10^-15 and 2bii show that 51V had a nuclear radius of 5*10^-15
Original post by Sam.B57
2bi and 2bii were both show that questions I think: 2bi show that r0is roughly 1.4*10^-15 and 2bii show that 51V had a nuclear radius of 5*10^-15


Oh yeah I got them, but I remember I got 1.33 or something for r0

For the moderator I wrote about a control rod instead, said keeps reaction under control by releasing 1 neutron per fission.
Original post by ubisoft
Oh yeah I got them, but I remember I got 1.33 or something for r0

For the moderator I wrote about a control rod instead, said keeps reaction under control by releasing 1 neutron per fission.


For the moderator I put that kinetic energy from neutrons is transferred to thermal energy in the moderator due to aournd 50 collisions-I'd seen that somewhere in a similar question on a past paper
Original post by Sam.B57
For the moderator I put that kinetic energy from neutrons is transferred to thermal energy in the moderator due to aournd 50 collisions-I'd seen that somewhere in a similar question on a past paper


That should be right

do you know how many marks the last few questions were?
Original post by ubisoft
That should be right

do you know how many marks the last few questions were?


The last few were thermal calculations, right?
Reply 3617
Original post by ubisoft
That should be right

do you know how many marks the last few questions were?


The very last question was 2,1,2 wasn't it?

2 assumptions about the motion of the particles, 1 for the mean square speed, and 2 for working out the average kinetic energy of the molecules.
Original post by bwr19
The very last question was 2,1,2 wasn't it?

2 assumptions about the motion of the particles, 1 for the mean square speed, and 2 for working out the average kinetic energy of the molecules.


sounds about right
Original post by ubisoft
Thanks for that. Do people have any different answers? Let's make a mark scheme for section A at least. And can someone confirm if the marks are all correct?

For 2a I got electromagnetic, but I think that would get marks as well
What was 2b and 2bii? I remember getting 1.3 as well but I used the value I worked out not the one they give.


I can confirm that he is correct on all those. Does anyone need a summary of the six marker?

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