Chelsea_12345
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Hey guys, I have many doubts in this paper. May June 2015 12. I’ll just list the questions

Q10 - I actually think the question might be wrong. I think they meant velocity before and after 5 seconds because the answer give by mark Chen’s would be correct if it is velocity. But mostly I’ll be wrong so please explain!😄
Q15 - no clue
Q17- I tried after looking at the answer and got the result but don’t know why.
Q23 - no clue
Q24- no clue
Q34 - no clue

Thanks guys.
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uberteknik
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(Original post by Chelsea_12345)
Hey guys, I have many doubts in this paper. May June 2015 12. I’ll just list the questions

Q10 - I actually think the question might be wrong. I think they meant velocity before and after 5 seconds because the answer give by mark Chen’s would be correct if it is velocity. But mostly I’ll be wrong so please explain!😄
Q15 - no clue
Q17- I tried after looking at the answer and got the result but don’t know why.
Q23 - no clue
Q24- no clue
Q34 - no clue

Thanks guys.
Which paper are you referring to: 1, 2, 3 or 4?
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Eimmanuel
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(Original post by uberteknik)
Which paper are you referring to: 1, 2, 3 or 4?
OP is referring to Paper 1v2 or in short paper 12.
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uberteknik
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(Original post by Eimmanuel)
OP is referring to Paper 1v2 or in short paper 12.
Thanks.
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Eimmanuel
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(Original post by Chelsea_12345)
Hey guys, I have many doubts in this paper. May June 2015 12. I’ll just list the questions

Q10 - I actually think the question might be wrong. I think they meant velocity before and after 5 seconds because the answer give by mark Chen’s would be correct if it is velocity. But mostly I’ll be wrong so please explain!😄
Q15 - no clue
Q17- I tried after looking at the answer and got the result but don’t know why.
Q23 - no clue
Q24- no clue
Q34 - no clue

Thanks guys.

I would suggest you take a snapshot of each questions and post them separately.

I would answer a few of them in short.

Nothing is wrong for question 10.
It is acceleration NOT velocity. I don't know Mark Chen...
The key concept is to recognize that the mass of the rocket is NOT constant.

Q15 Look for center of mass also known as center of gravity. The change in height is the change in the height of the center of mass.

Q17 Conservation of energy.

Q23 is a difficult question for most students. The key things is to recognize that the area of the "thin" wall is proportional to w.

Q24 A phase difference of 100° is equivalent to 260°.


Q34 I think is uberteknik's favourite...
Note that
E - Ir = IR
and multiply the equation by Q.
EQ - IrQ = IRQ
Do some rearrangement, you would get the answer.


I would write a more detail explanation when I have time. Sorry for the short answer and if it does not help.
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Chelsea_12345
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(Original post by Eimmanuel)
I would suggest you take a snapshot of each questions and post them separately.

I would answer a few of them in short.

Nothing is wrong for question 10.
It is acceleration NOT velocity. I don't know Mark Chen...
The key concept is to recognize that the mass of the rocket is NOT constant.

Q15 Look for center of mass also known as center of gravity. The change in height is the change in the height of the center of mass.

Q17 Conservation of energy.

Q23 is a difficult question for most students. The key things is to recognize that the area of the "thin" wall is proportional to w.

Q24 A phase difference of 100° is equivalent to 260°.


Q34 I think is uberteknik's favourite...
Note that
E - Ir = IR
and multiply the equation by Q.
EQ - IrQ = IRQ
Do some rearrangement, you would get the answer.


I would write a more detail explanation when I have time. Sorry for the short answer and if it does not help.
Hey, thanks for the reply mate. I understood 15,17,24 and got the answer. But I still do not understand 10,23,34. . so for the 10th question I understand that mass will be changing. So the before 5 sec part the acceleration will be increasing. But after 5 secondswith no fuel left and constant mass there will be no force. It will go at a constant velocity so should the acceleration not be 0? If it is 0 the answer is D but it is wrong. And I also don’t get the 23 and 34. Part. So If u have time please explain them further. Thanks😄.
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hafiza1782
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for Q24, what does it mean by 100 equivalent to 260? Is there any maths calculation?
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Eimmanuel
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(Original post by hafiza1782)
for Q24, what does it mean by 100 equivalent to 260? Is there any maths calculation?
There are several ways that you can work out or show that “A phase difference of 100° is equivalent to 260°” using diagram or maths calculation.

The first method is using the diagram given in the question.
To work out the phase difference between two waves, choose two points which are in phase in the two waves of the same frequency.
I have marked out the points in Fig 1a as shown below. Note that the orange point is equivalent to the green point in wave 1.
The phase difference between the orange point in wave 1 and red point in wave 2 is 100° as indicated by the blue arrow while the phase difference between the green point in wave 1 and red point in wave 2 is 260° as indicated by the purple arrow.
Thus, a phase difference of 100° is equivalent to 260°.

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