Physics 3/4 Exam Discussion

[zsteve]

I got 16.7 degrees, anyone else (using the 3 m/s value)

Yup the question said 3 m/s not 2 m/s (tricky - I noticed it when rereading)
And did anyone get the last question for Sound? I had no idea - and my teacher had no idea either, she thinks VCAA messed it up. I made a guess and chose B

[dankfrank420]

Do you guys think a 40 is achievable with like 130/150? I know ive definitely lost 10 marks

Exam was of roughly similar difficulty, so I'd say a+ cutoff will be about 130.

[bobisnotmyname]

Even though I picked up on the changed speed, I think that was a pretty dodgy move by VCAA, the exam shouldn't be about trying to trick people but testing their knowledge, they simple should have more involved questions. As for calculating that angle, I still don't understand the tan(theta) rule but it works . Also how do we do the total power loss question, I simple did p=I^2R, but it was a 3 mark question...

[sharans]

Hey Steve, I chose B first as well

But I figured out it can't be B as the wavelength was something like a 0.25 m (assumed speed to be 340 and used frequencies given in the question)  and the rooms definitely larger than that. So I chose D

[dankfrank420]

Did anyone think the first question was deceptivelly tricky for a first question?

[Ysera]

Exam was of roughly similar difficulty, so I'd say a+ cutoff will be about 130.

Yeah, i dont think the cut offs will change, it was easy similar to last years, I'd think you can get 40 raw with that. What did you guys get for the spring question for the maximum speed?

[sharans]

Did anyone think the first question was deceptivelly tricky for a first question?

Yeah nearly missed on that "rebound". Did you use negative velocity for the rebound though?

[Butterscotch]

Even though I picked up on the changed speed, I think that was a pretty dodgy move by VCAA, the exam shouldn't be about trying to trick people but testing their knowledge, they simple should have more involved questions. As for calculating that angle, I still don't understand the tan(theta) rule but it works . Also how do we do the total power loss question, I simple did p=I^2R, but it was a 3 mark question...

I did the same, got Ploss as 16W... Not sure if trick ques or easy marks :')

[dankfrank420]

Yeah nearly missed on that "rebound". Did you use negative velocity for the rebound though?

Yes, so the momentum of the b block was 40 I think.

[zsteve]

Hey Steve, I chose B first as well

But I figured out it can't be B as the wavelength was something like a 0.25 m (assumed speed to be 340 and used frequencies given in the question)  and the rooms definitely larger than that. So I chose D

Yeah I calculated the wavelengths, but D talked about destructive interference, so it looked like it was wrong. The 'reflections' point is valid, but how did you justify the second part, talking about 'destructive interference'? It has nothing to do with the situation!

[Orson]

Yes, so the momentum of the b block was 40 I think.

Impulse going left?

[zsteve]

Impulse going left?

Yes =)

[dankfrank420]

Impulse going left?

Yes, the impulse going left was also 40 I think.

[sharans]

Yeah I calculated the wavelengths, but D talked about destructive interference, so it looked like it was wrong. The 'reflections' point is valid, but how did you justify the second part, talking about 'destructive interference'? It has nothing to do with the situation!

I might be wrong, but option D looked the least incorrect to me. Would shoot myself if B was the correct answer, cos I chose B and then changed it to D.
Xd

[WendyIbrahim]

Please tell me I wasn't the only idiot who didn't have anything about ionisation levels on their cheat sheet and fked that whole question up