Physics Paper 23

[roneyms]

For the electricity question I did someone like V=IR for the first two parts (I used it somewhere to find I I think, and later put it in the equation E/R+r=I so yeah)

I left the last part lolll. The last part has something to do with internal resistance.

 

[DominicD]

The expression of I is, I=E/(R+r), E is the y-intercept = 5.8V, power dissipated when I=1.6A is P=VI = 2.9x1.6 = 4.64W, and lastly the efficiency part is just VI/EI x100% = 50%

 

[roneyms]

Yeah I got those too, I just missed the last part.

 

[DominicD]

I think generally the paper isn't hard. It is different and for some people, it looks tricky.

 

[Rickster]

Thanks for the explanations
I think most people did not expect that resitive force question, the resultant vector question and the electromagnetic spectrum question.
Also at the end, for that nuclear equation, i think one of the particles was 3-2 He. I thought He was 4-2 ( 4 nucleons and 2 protons?) Is it like an isotope?
Thanks

 

[DominicD]

I wasn't expecting that much of drawing and calculations for gradients. >__> Tedious work.
It is definitely helium-3, isotope of helium-4.

 

[Rickster]

Also, for that question where the ball rolls down the slope. When they tell you to calculate the velocity and time to reach the bottom, can you assume that kinectic energy = potentital energy, since there is no friction. Would this give you the velocity when it reaches the bottom?

 

[DominicD]

I think that works. I however used v^2=2(gsin15)(0.28/sin15), well it's the same anyway.