# physics exam (1 Viewer)

#### mzduxx2006

##### Member
OMG FUKIN HARD I SWEAR. it had sooo many mathematical equations. like wtf? :O *cries*

#### flowergrl

##### Member
Twas my easiest exam EVER!!!!!

What u on about???

But there was one glitch. The P release thing projectile motion thing.

It didn't state if it wanted an initial or final horizontal velocity at P so I thought it was a trick question.

Clearly, initial velocity was 0 for horizontal and vertical as it was "released". DUH. But what horizontal v did it want? At P or what? So I wrote 2 solutions but I didn't get to use the calculator for the second part so I just wrote the multiplication: .89=Ut=something- i forgot.

Anyway, since that was my final exam, I'm feeling generous to post up the MC solutions that may or may not be right, but I'm pretty confident:
1) A
2)A
3)B
4)D
5) D
6) D
7)C
8)D (haha, trick question...)
9) C
10) A
11) D
12) B
13) B
14)C
15) A

So how did everyone else go???

#### Nosviper

##### Member
I got different answers to you. I could swear for the first page it asked for the horizontal velocity at P. THats what I found anyway

1) A
2) A
3) B
4) D
5) D
6) D
7) C
8) B
9) C
10) A
11) D
12) D
13) C
14) A {key word = property}
15) A

#### BtheVoid

##### New Member
Ffs you reminded me about the question i was supposed to go back to but didnt.
:burn:

I found it hard :\ The last few multiple choice questions were tricky. I had no idea how to find the altitude of the satilite, seeing as they only gave us radius and mass of the earth..
In the photoelectric effect, I knew the gradient was supposed to be H but i couldnt get that through rise/run so I just fudged it. :s
There were a few questions in astrophys i spent to long on, and I think that hurt me on the 7 marker and the last part because I couldnt write as much as i should have. Asking us to plot all the stars on my cruddy diagram was also fairly cruel.

#### TylerAshwell

##### New Member
i got something like 32 917 or maybe 35 917 for altitude of the satelite. Can't really remember what they gave as the radius of the earth but it was 42,297,523.87m -radius of earth in m. I just used Keplers law thing: with T as 86400 seconds, because the period of a geostationary orbit is the same as the earths rotation of 24hours. I am probably wrong though

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#### Vasc0

##### New Member
Actually 8 was C. To find the emf on coil it is the gradient of the magnetic flux. the gradient of the flux at 0 is + therefore it has to be C.
I also got 12 A, 14C and 15B.

Although it said property in 14 a silicon p type semiconductor is not positively charged! and with 15 if you use e = mc^2 you can find the energy of the proton at rest, i thought that corresponded to the law of conservation of energy somehow but I guess not.

#### eXegio

##### New Member
nay, 'tis D. emf is - (change in flux) / (change in time)

ack, for that satellite question ... i actually thought of the right thing but couldnt be bothered to use it (orbital velocity = 2(pi)r/T ... which is kepler's law if u equate it)

ended up getting a wrong answer and was gonna come back to it to do it properly but totally forgot ... i dunno what got into me

i rekon the most confusing question was Q10. Hertz measured the velocity of light through ... wth~ they're ALL right: he reflected (and refracted) radio waves into a loop and the polarisation caused sparks from which he used the interference pattern of the nodes and anti-nodes to work out ....
(i said it was C (reflection) but i think it's wrong in retrospect~ sigh~ that's 4 marks gone straight off the bat~)

#### MCC2529

##### New Member
I am fairly sure that if that physics paper some how became a person, It would hunt me down and rape me from behind again. Not a fan of physics anymore. But hey. Ill never have to hear about it again so go me!

#### dwatt

##### Member
Question 8 I had D as well. I very nearly put 8. But yes, emf is change in flux/change in time.

Think of a generator. When it is parallel to the plane of the field, the greatest change is ocurring, though flux is least. When the coil is at right angles to the plane of the field, max flux is going through, yet emf is a minimum.

D was the only one that fitted it in my opinion

12) A. X-rays are scattered (diffracted) aren't they?

14 was c. P-types are neutral! But...i don't know how people can classify "can be produced" as a property. Oh well.

15...I had d). I thought the energy of a proton at rest was dependent on energy conservation (E = mc^2). Cos when you put in more energy it is converted into mass right, but the energy is still equivalent.

Probably screwed that up though

#### farahodish

##### Member
dwatt said:
14 was c. P-types are neutral! But...i don't know how people can classify "can be produced" as a property. Oh well.

15...I had d). I thought the energy of a proton at rest was dependent on energy conservation (E = mc^2). Cos when you put in more energy it is converted into mass right, but the energy is still equivalent.

Probably screwed that up though
OHEMGEE me TOOOO!
i got those as well, and they STILL sound right to me LOL please someone say they're right.

and ohmygosh at the freaking radius/satellite thingo..
I FORGOT THAT KEPLER"S LAW EVEN EXISTED?!
so i just said that a geostationary orbit is usuall 35800km and subtracted the other number from it.
which is wrong but LOL

AND OHHHHMYYYGOSHHHH!!!

NO PRACS NO PRACS NO PRACS!!!!!!!:rofl: :rofl: :rofl: :rofl:

#### Ozza

##### Member
I asked my teacher... said that 12 wost most likely A, 15 D and 10 was C only because it said calculating the velocity of raido waves relative to light.

#### Nosviper

##### Member
Farodish I did that aswell... we will get marks for it cause it was out of three for recongnising the geostationary orbit. Maybe even full marks

#### Chinmoku03

##### Ippen, Shin de Miru?
Easiest exam I've done outta all my subjects. Funny how I got thrown off by the 2 mark projectile motion for the horizontal velocity XD

But eh, I'm happy with how I did ^.^

#### farahodish

##### Member
Nosviper said:
Farodish I did that aswell... we will get marks for it cause it was out of three for recongnising the geostationary orbit. Maybe even full marks
ohhh GOD BLESS YOUUUU!! YAY YAYAYAYAYYYY!!
and to the other one on top of me, which i cant be bothered quoting,
WTF at that projectile question.

it was like one of the FIRST questions, and worth 2 marks so it shouldnt have been hard!! :burn:

#### Shrikar

##### MλĐ€ IŇ ĮŃĐĨλ
Chinmoku03 said:
Easiest exam I've done outta all my subjects. Funny how I got thrown off by the 2 mark projectile motion for the horizontal velocity XD

But eh, I'm happy with how I did ^.^
Did you get like 19.8 ms-1 for the horizontal velocity?

#### jah_lu

##### Member
yeh i definitely seemed easier than previous years
although i found the einstein question hard
mc answers for me are
1A
2A
3B
4D
5D
6C
7C
8D
9C
10A
11D
12A
13C
14C
15A

unsure about 12 (i think its a) and 14 (i swaer i rem hearing its not positively charged)

#### Forbidden.

##### Banned
τ = Fd = nBIAcosθ
mgd = nBIAcosθ

n = mgd / BIAcosθ

???

Weight at point X ???

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#### dwatt

##### Member
Shrikar said:
Did you get like 19.8 ms-1 for the horizontal velocity?
That crappy little question...hated that. I'm convinced I have done something really wrong but here is what I had:

I had range at 80cm, at about 92cm (or there abouts). I worked out it took about 0.2 seconds for the ball to fall 30 centimetres (maybe it was 2-3...don't remember).

So, V = s/t was about 2-4 m/s.

So sorry I cannot remember ANY of the numbers I used. But this is the method I used. Was this stupid?

#### anniea89

##### Member
I got 38. something cm/s for the projectile q........

It was ok, better than chem, but I stuffed up the option (quanta to quarks).

#### dwatt

##### Member
Forbidden. said:
τ = Fd = nBIAcosθ
mgd = nBIAcosθ

n = mgd / BIAcosθ

???

Weight at point X ???

Yeah this was weird this one.

I had T = Fd for the weight. D was 0.1 m, 10cm was radius of perp. point to line of force. Force was given by mg. Let's say torque = x

If this torque was just enough to balance it, then x = NIAB (Costheta = 1)
so n = x/(IAB)

....i just realised that is exactly what you said. So i hope we are both right.