Physics: Discussion, Questions & Potential Solutions

[Theodric_Ironfist]

How did we meant to draw the 3 mark graph of emf idk i drew my like sin

Square wave; zero for the loop outside and inside sections, positive for loop entering, negative for loop exiting.

[aussiboi]

do you guys think it was harder or easier than last years? Potential A+ cut offs?

[EffAyeP]

That exam was a welcome surprise. Explain type questions were my weakness all year, yet there were almost none of them, and none over 3 marks.
 
How far did the student between two speakers walk to get to the 2nd quiet band? I got the PD of 1.5m, then halved it to get 0.75m walked.

[Theodric_Ironfist]

The exam was probably a bit simpler than last years. Cutoff for A+ might be higher.

I do think that question 5d (second experiment with transformer at 8:1) and the whole of question 6 were badly written though.

Multiple choice was extremely easy.

[jpulvirenti]

That exam was a welcome surprise. Explain type questions were my weakness all year, yet there were almost none of them, and none over 3 marks.
 
How far did the student between two speakers walk to get to the 2nd quiet band? I got the PD of 1.5m, then halved it to get 0.75m walked.

the wavelength was 1m?
Therefore 10 wavelengths in 10m. at centre it is quiet. walk along 1 wavelength to get 1m?
I got 1 meter from centre

[Theodric_Ironfist]

the wavelength was 1m?
Therefore 10 wavelengths in 10m. at centre it is quiet. walk along 1 wavelength to get 1m?
I got 1 meter from centre

Wavelength is 1 m.

They are standing at 2nd node, so PD = (2-0.5) x 1 = 1.5 m

If they are standing at point P, then AP - BP = 1.5, and AP + BP = 10.

Thus AP = 5.75 m and distance from center is 0.75 m

[aussiboi]

i thought its 4th node because they gave you the PD already??

[EffAyeP]

the wavelength was 1m?
Therefore 10 wavelengths in 10m. at centre it is quiet. walk along 1 wavelength to get 1m?
I got 1 meter from centre

Wavelength is 1m
PD is 0 in the middle
2nd quiet means PD is 1.5*wavelength = 1.5m

Walk 0.75m to get closer to one speaker, and further from the other, creating a PD of 1.5m

0.75m

Could be wrong

[jpulvirenti]

Wavelength is 1m
PD is 0 in the middle
2nd quiet means PD is 1.5*wavelength = 1.5m

Walk 0.75m to get closer to one speaker, and further from the other, creating a PD of 1.5m

0.75m

Could be wrong

I drew 10 sine waves connecting speaker a and b., then reverse for standing waves.
here is what i did. a bit messy Lol

[Theodric_Ironfist]

So the stupid spring question....

It states "the ball and spring come to rest when they are at a distance of 0.50 m below the uncompressed position of the spring."

To me, that sounds as if the ball and spring have stopped oscillating. Thus the forces are balanced, and mg = kx, and thus k = 39.2 N/m.

If it means the lowest point that the ball reaches, then it should have specified MOMENTARILY at rest. In which case you use an energy approach and you end up with k = 392 N/m. But the lack of the word MOMENTARILY changes the question completely.

Not to mention the rest of the question. Are we to assume that now the ball has stuck to the spring and is undergoing an oscillating motion? And we are to analyse the motion of the ball after it has stuck, disregarding the first part of the ball's motion? Because then the question makes sense. BUT NO WHERE DOES IT SAY TO DO THAT!

Rant over, sorry guys.

[lolno]

My MC Answers please compare and give me a grade! (I am a C+ student)

1.) B
B
A
D
C
C
A
C
B
A
11.) D
D
D
B
C
C
A
B
B
B

[aussiboi]

I got nearly the same just 5 qs different

[Theodric_Ironfist]

MC Answers:
B
A
A
D
C
C
B
C
B
D
D
C
D
B
D
C
A
A
B
B

[izam25]

What did you guys get for the very last question? (if you remember lol)

[jpulvirenti]

What did you guys get for the very last question? (if you remember lol)

This q will vary between students due to gradient calculation.
i god 6.x10^26. dont remember the decimal