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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. What are the grade boundaries like for unit 2? What do you all think they will be for this exam?

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2. (Original post by FLLF)
Did anyone get the weight of the ball to be 0.44N (or thereabouts). I was confused by this question at first until I saw the formula for the volume of a sphere.

Overall I thought it was a harder than average paper, so the grade boundaries will be lower-normal.
Yep, 0.44N to 2dp! Grade boundaries I reckon could be 46-48/70 for A as it was a bit tougher than some of the others for sure!
3. (Original post by FLLF)
Did anyone get the weight of the ball to be 0.44N (or thereabouts). I was confused by this question at first until I saw the formula for the volume of a sphere.

Overall I thought it was a harder than average paper, so the grade boundaries will be lower-normal.
I got 0.44 at first (that is correct), but then I changed it as a I though it was too low, I got 44 haha, how many marks do you think I will loose for all correct working but wrong answer?

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4. Hoping that everyone failed so grade boundaries are very low! Otherwise i'm screwed
5. (Original post by GeorgeBarrett1)
I got 0.44 at first (that is correct), but then I changed it as a I though it was too low, I got 44 haha, how many marks do you think I will loose for all correct working but wrong answer?

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It depends, it was out of 4, so I would say at least 2 and if were being optimistic 3
6. The graph was wider and lower in intensity:

intensity is the energy of photons: E= hc/wavelength therespre increasing wavelength decreases energy which decreases intesity.

Thats what my teacher told me.
7. (Original post by GeorgeBarrett1)
I got 0.44 at first (that is correct), but then I changed it as a I though it was too low, I got 44 haha, how many marks do you think I will loose for all correct working but wrong answer?

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8. First question

Can anyone confirm: 6100N, about 9 degrees, and like 22% for the efficiency???
9. Not an entirely nice exam. I'm guessing 60/70 for 120 UMS, as for the past 3 years it's always been 61 or below for 120 UMS?
10. I honestly think I'd be lucky to get a C, my maths was all over the shot.
11. (Original post by FLLF)
First question

Can anyone confirm: 6100N, about 9 degrees, and like 22% for the efficiency???
Yes

22.2% i got for effiencity and the same as you for the rest.
12. (Original post by FLLF)
First question

Can anyone confirm: 6100N, about 9 degrees, and like 22% for the efficiency???

I got 6082N (rounds to 6100N). Something like 9.5 degrees, and yes, about 22-24% for efficiency (can't remember exactly).
13. How about the graph everyone? I drew the maxima more spaced out, but did you have to do something with the intensity? Thanks!
14. Yes (9.5) and yes!!
I also got 0.44N
(Original post by FLLF)
First question

Can anyone confirm: 6100N, about 9 degrees, and like 22% for the efficiency???
15. (Original post by Zakee)
I got 6082N (rounds to 6100N). Something like 9.5 degrees, and yes, about 22-24% for efficiency (can't remember exactly).
Useful power was Ep/55 seconds

So that/320000 x100= 24 or whatever
16. Think I got this one wrong! I knew that they were spread out, so got that mark.. but I think the intensity should have been lower..
(Original post by FLLF)
How about the graph everyone? I drew the maxima more spaced out, but did you have to do something with the intensity? Thanks!
17. 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
18. It was 1.0J as it was to 1 significant figure But hopefully they'll accept anything around that.
(Original post by samueliscool)
Indeed, it counted each square as 1 rather than whatever it was for each square stupid mistake, thanks anyway
19. (Original post by FLLF)
First question

Can anyone confirm: 6100N, about 9 degrees, and like 22% for the efficiency???
Yes yes and yes
20. (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:
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:
Can't remember

Question6: Progressive wave one
1/2pi and 3/2 pi
Describe motion of B (up then down then down then up)
Transverse so seismic S wave?
Define frequency
Wavelength (750m)

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
Question five -

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

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