AQA Physics Unit 2 Higher Unofficial Mark scheme

The question was which particles are more likely to cause an explosion. Surely in this highly important Physics exam worth 25% of your GCSE, reading the question could be considered.

First full correct UNOFFICIAL mark scheme for AQA Physics Unit 2 Higher - 30th Jan 2012


1
a)
i) Electrons transferred from pipe to beads causing beads to become negatively charged.
ii) 75cm^2 beads
iii) As the size increases the charge decreases.

b) Pipe is smaller and so less overall charge is transferred to the beads.

c)
i) Fine particles have a larger surface area.
ii) Earth pipes.
iii) These variables will affect the overall results.

2
a)
i) Nuclear fission is the separation of a heavier nucleus into lighter nuclei by 'firing' neutrons into the nucleus. This also releases more neutrons. Nuclear fusion is the fusing of lighter nuclei to form a heavier nucleus.
ii) Energy/heat

b)
i) Uranium 235
ii) Protons

3
a) Constant speed, accelerating, decelerating

b)
i) Braking Distance
ii) Speed

c)
i) 5000N in the opposite direction (to the left) - Newton's third law.
ii) Measure force exerted on specific points of the dummy.
iii) 4m/s^2

4
a)
i) 2V
ii) Straight line up to (0.8, 2), then a curve to (2, 12)
iii) As heat increases the filament in the lamp becomes more resistant.

b) 108J

5
a) They realised the pudding must contain a positive charge.

b)
i) Experiments didn't support the pudding model, and so it could not be correct.
ii) Not deflected, partially deflected, almost fully deflected by gold atoms.

c) Showed that the nuclear model was correct.

6
a) 98J
b) 9.6 kgm/s
ii) 9600N
iii) Force is equal to change in momentum (mass x velocity) over change in time. If change in time increases then overall force decreases.

Instead of earth the pipes, I said make the particles bigger because there would be less charge, hence less chance of an explosion. Would I be given the mark?

Hello. I am really concerned about how i have done. Here are my answers could someone give me a mark what they believe is likely and a equivalent grade considering the paper and the qeustions?

1a) Friction between the pipe and the beads causes electrons to transfer from the pipe onto the beads, meaning they have more electrons than protons,making them negatively charged.
ii) The volume of the beads used (75cm^3)
iii) As the size of the beads increases, the charge decreases
b) The charge decreases because the pipe is shorter, and therefore there is less friction and therefore less electrons are transfered
c) Fine powders because they have a larger surface area for friction and therefore more charge builds uo
ii) Earth the pipes
iii) To make the results more accurate
2a) Nuclear fission is the proccess where a large atomic nucleus splits into to smaller atomic nuclei fragments, wheras, nuclear fusion is the proccess where two small atomic nuclei join (fuse) together to form a larger atomic nucleus
ii) Energy
b) i) Uranium -235
ii) Same number of protons
3a) Constant speed, accelerating, decelerating
b)The distance travelled by the vehicle during the time that the braking force is applied
ii) Speed
c) 5000N in the opposite direction to the car
ii) To measure the dummy's velocity( so the force extered on it could be calculated)
iii) 4m/s^2
4 a) 2V
ii) A straight line from the origin to 2,0.8 and then a curve rising up and passing through 12,2
iii) Because there is more friction
b) 108J
5 a) That it is positively charged( they asked what does this mean about matter behind the negative charged particles)
b) Because it led to the discovery of the nucleus ( they asked why did the Rutherford experiments lead to the plum pudding model not used)
ii) A-The alpha particles went straight through and didn't go near the postively charged nucleus so it was not repelled and therefore it wasn't effected
B-The nucleus is small and has a positve charge and the alpha particles go near to the nucleus causing them to repel and being deflected off
C-The nucleus is small and has a positive charge and the alpha particles hit the nucleas and are repelled and reflected of but only a small number reflected because the nucleus is small
c) To make his theories and results more reliable
6a) 98J
b) 4.8 kgm/s ( wrong asnwer but i hope to get a mark for my working out)
ii) 4800N
iii) It increases the time taken for the ball to stop which reduces the change in rate of momentum and therefore reduces the force exerted on the fielders hand

Mark,Grade,Comments?
:/

Hello. I am really concerned about how i have done. Here are my answers could someone give me a mark what they believe is likely and a equivalent grade considering the paper and the qeustions?

1a) Friction between the pipe and the beads causes electrons to transfer from the pipe onto the beads, meaning they have more electrons than protons,making them negatively charged.
ii) The volume of the beads used (75cm^3)
iii) As the size of the beads increases, the charge decreases
b) The charge decreases because the pipe is shorter, and therefore there is less friction and therefore less electrons are transfered
c) Fine powders because they have a larger surface area for friction and therefore more charge builds uo
ii) Earth the pipes
iii) To make the results more accurate
2a) Nuclear fission is the proccess where a large atomic nucleus splits into to smaller atomic nuclei fragments, wheras, nuclear fusion is the proccess where two small atomic nuclei join (fuse) together to form a larger atomic nucleus
ii) Energy
b) i) Uranium -235
ii) Same number of protons
3a) Constant speed, accelerating, decelerating
b)The distance travelled by the vehicle during the time that the braking force is applied
ii) Speed
c) 5000N in the opposite direction to the car
ii) To measure the dummy's velocity( so the force extered on it could be calculated)
iii) 4m/s^2
4 a) 2V
ii) A straight line from the origin to 2,0.8 and then a curve rising up and passing through 12,2
iii) Because there is more friction
b) 108J
5 a) That it is positively charged( they asked what does this mean about matter behind the negative charged particles)
b) Because it led to the discovery of the nucleus ( they asked why did the Rutherford experiments lead to the plum pudding model not used)
ii) A-The alpha particles went straight through and didn't go near the postively charged nucleus so it was not repelled and therefore it wasn't effected
B-The nucleus is small and has a positve charge and the alpha particles go near to the nucleus causing them to repel and being deflected off
C-The nucleus is small and has a positive charge and the alpha particles hit the nucleas and are repelled and reflected of but only a small number reflected because the nucleus is small
c) To make his theories and results more reliable
6a) 98J
b) 4.8 kgm/s ( wrong asnwer but i hope to get a mark for my working out)
ii) 4800N
iii) It increases the time taken for the ball to stop which reduces the change in rate of momentum and therefore reduces the force exerted on the fielders hand

Mark,Grade,Comments?
:/

i could not remember what the number was for uranium so i put uranium isotope, do you think i would get the mark for that, also 3cii i put something along the line of: to test the effect the force has on the dummy.

Yes for the uranium, and maybe for the dummy one, the question wasn't that specific about what it wanted you to put. I think, however, you would get a mark for that.

You're looking at a high mark there, apart from 6 a and b you may have lost very few marks. A* for sure.

4a) iii. was that as the lamp filament increased in temperature the resistance also increased. Nothing to do with friction.

On the question about the car. Would saying "5000N in the opposite direction to the car"get the mark because it did say state the force and direction and there was room for writing. I didnt say draw it onto the image. Anyone know whether or not that is correct or are the exam board going to be fustrating and say there had to be a image even though it clearly didn't say you needed one?

Thankyou

thank you

Do you think that I will definitely get a A* and what sort of mark do you thik i will get ?

Thankyou

Certainly as you're looking at about 40/45 marks. The grade boundary for A* is usually 30-35 depending on how difficult it was, and how everyone else did.

So you definatelty think i will. And with regards to the car thats what i said. 5000N in the opposite direction to the car. This means that if the car was going right, the force would go left, meaning that the force is against the car?

Would i get the mark for that now as i have explained it a bit more?

Yes that is correct, the force is exerted into to the car. Sorry I got confused by the way you put it.

You should have done very well