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# The Physics PHYA2 thread! 5th June 2013 watch

• View Poll Results: What mark do you think you got out of 70?
0-20
6
3.00%
21-40
12
6.00%
41-50
29
14.50%
51-60
79
39.50%
61-70
74
37.00%

1. (Original post by FLLF)
First question

Can anyone confirm: 6100N, about 9 degrees, and like 22% for the efficiency???
Yep i think so!
2. (Original post by Frogs491)
6100N
9.5degrees
Acceleration
Ep
Power efficiency 20.4

Question2:
0.55s
245m ish as square route of 2y/g
S=Vt so if V is lower S is lower acceleration is equal for both across same distance therefore same vertical downwards time however lower horizontal velocity in b means lower distance as S=Vt

Question3:
volume of sphere equation density over volume value is 0.44n weight
The ball in oil including newtons first and second law terminal velocity resultant forces and gravity vs drag to create curve of velocity followed by horizontal etc(6 marks)
Then graph- straight line until it goes in then curve to decreasing gradient until gradient=0 and stays constant

Question4:
Hookes law
Gradient for k (1100 N/m ish
Area under- 1/2F x delta l can't remember value
Straight line parallel to first one intersecting x axis
plasticity definition (look it up)
Work is less as area under graph is less energy absorbed as heat and in permanent extension

Question5:

Two conditions for TIR? Higher than critical angle, and moving from a higher n to lower n.

Speed of light = 1.7*10^8

Angle =30 degrees

Critical angle = 51 degrees

What happens to the ray of light? Undergoes TIR since angle of incidence = 52 degrees > critical angle

Draw light reflecting off thanks to flf

Question6: Progressive wave one
1/2pi and 3/2 pi
Describe motion of B (up then down then down then up)
Transverse so seismic Secondary wave oscillations perpendicular to energy transfer, many oscillation planes turned to one therefore must transverse
Define frequency
Wavelength c=wavelength x frequency therefore answer forgotten values

Question7:
Definition of monochromatic
Fringes larger intensity equal
Forgot
White light fringes vs monochromatic fringes red outside fringes blue light inside white central colours diffract at different angles therefore overlapping etC
Well **** me, I think I may get a B at most
3. Used area of sphere accidentally instead of volume when calculating weight. How many marks will i lose? I wrote out formula so examiner can see where i went wrong.
4. (Original post by nich01as)
Btw, any thoughts on the 100% ums mark? The mean of previous years in 60, with 57 being the lowest, 69 being the highest, and 62 being the second highest. Any thoughts? Harder than normal, easier? Thanks.
Where can you find the UMS boundaries?
5. (Original post by FLLF)
I got the same answer, there will be a range of accepted values, and 1.1 will be in there

I absolutely hate those questions though. It takes no real skill, only toil to actually calculate the area. I probably spent an hour of the paper calculating the area of the squares than I did on the Physics.
6. really annoyed i messed up the graph drawing 3 marker...
7. (Original post by Anonymous1717)
Where can you find the UMS boundaries?
8. (Original post by Anonymous1717)
Where can you find the UMS boundaries?

For our specification (2010 onwards)

The grade boundaries have varied (for 120/120 UMS).

From 57-62. With a mean of 59. I am going for around 59-60 for 120 UMS for this paper. There were many more places people could have slipped up on than the 62/70 120 UMS papers. It wasn't a great paper to be honest (I am one of those people who made stupid, foolish deluded errors >.>)
9. (Original post by Zakee)

For our specification (2010 onwards)

The grade boundaries have varied (for 120/120 UMS).

From 57-62. With a mean of 59. I am going for around 59-60 for 120 UMS for this paper. There were many more places people could have slipped up on than the 62/70 120 UMS papers. It wasn't a great paper to be honest (I am one of those people who made stupid, foolish deluded errors >.>)
good to know thanks

still an outside (very outside) chance of 120
10. (Original post by J Dilla)
really annoyed i messed up the graph drawing 3 marker...

Don't worry, for the question on optics about what happens, I said 22 + 30 = 22, and so I said it would be refracted, when instead it was TIR.
11. Made a few silly mistakes here and there, but thought it was an OK paper.
12. (Original post by J Dilla)
good to know thanks

still an outside (very outside) chance of 120

As have I.
13. I'm surprised a lot of people here calculated the work done by counting the squares. Using the shaps properly should of given the correct answer quite easily, and only really takes about 2 minutes.
14. Someone make an unofficial mark schemeeee who has a copy of the paper?
15. How were you supposed to draw the graph of the second ball in the container that wasn't full with oil?
16. Wow I made so many stupid mistakes looking back it's actually hilarious...
17. Uhh, it did refract though. The angle of incidence was below that critical angle. Well, if you calculated the angles correctly that is.
18. For prove the angle is 30 degrees I got 31.9, as did 3 other people.

Did anyone else?
19. DRAW THE GRAPH QUESTION FOR BALL B:

You would show it accelerating at uniform motion (due to free fall), then doing the same thing that it did with the previous graph, slowly losing uniform acceleration and reaching constant velocity.
20. (Original post by Raimonduo)
Uhh, it did refract though. The angle of incidence was below that critical angle. Well, if you calculated the angles correctly that is.
But the angle of incidence was 52 and the critical angle 51 so there were reflection?

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