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Physics: Post your doubts here!

Charlotte20102013

Charlotte20102013

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Hi. I am currently in CAL and I would like to know about answering the questions on the Kirchhoff's rule questions. I understand that if I calculated a current with negative sign then the actual direction of the current is actually opposing the direction that I myself have fixed. At the end of my answer(if I got a negative answer) do I have to state things eg 'The current is 9.2A in the opposite direction' or something like that or? Please help. Thanks very much!
 
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Charlotte20102013 said:
Hi. I am currently in CAL and I would like to know about answering the questions on the Kirchhoff's rule questions. I understand that if I calculated a current with negative sign then the actual direction of the current is actually opposing the direction that I myself have fixed. At the end of my answer(if I got a negative answer) do I have to state things eg 'The current is 9.2A in the opposite direction' or something like that or? Please help. Thanks very much!
Click to expand...
How will current move in opposite direction? I might not get what are you asking. Can you tell me in which paper was the question like this? Coz I had solved almost every paper and I have not came across this (This is not possible). Upload the question. Or try it once again!
 
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Charlotte20102013 said:
Uhm... Can someone provide me the solution to my question please?
Click to expand...
I am so sorry I am late. Did you found out the answer or you want me to do?
If you still havent got it.
Here it is :¬
At node B: Ih = Ia + Ib
For Loop BCDE using KVL: 0 = 1.2*Ih - 12 + 0.01Ib
For Loop ABEF using KVL: 0 = 0.1Ia - 0.01Ib + 12 - 14

3 equations for 3 unknowns - the rest is math.

I would rarely be seen in threads. Coz now I am here and get busy in conversations of studies. Nothing confidential. So I am sorry if I cannot. And it would be better if you inbox me questions coz I prefer checking inbox first. I rarely click on alerts. As today. :) I totally forgot to reply you, but as I got alert, its here. Sorry again.
 
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The intensity I of a sound at a point P is inversely proportional to the square of the distance x of P
from the source of the sound. That is
I ∝ 1/x^2

Air molecules at P, a distance r from S, oscillate with amplitude 8.0µm.
Point Q is situated a distance 2r from S.
What is the amplitude of oscillation of air molecules at Q?

Question 26, May 2008.
papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s08_qp_1.pdf
 
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The intensity I of a sound at a point P is inversely proportional to the square of the distance x of P
from the source of the sound. That is
I ∝ 1/x^2
Air molecules at P, a distance r from S, oscillate with amplitude 8.0µm.
Point Q is situated a distance 2r from S.
What is the amplitude of oscillation of air molecules at Q?

May 2008, question 26.
 
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Physicist said:
actually, the only formula that come to me is F = kx. how to apply it here? I can't understand any of the answers provided, the calculation involved???

As well as telling me why B is correct, could you tell me why the others are wrong???


Thanks
Click to expand...
Probability A and B. I think you obviously know why the other two are rejected.
B because, no matter how many springs you add the total compression will be unchanged as each of the springs have the same spring constant.
A is not the answer coz, i think that should make it harder because each layer does not have the same force applied to it.
 
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Llamas said:
The intensity I of a sound at a point P is inversely proportional to the square of the distance x of P
from the source of the sound. That is
I ∝ 1/x^2

Air molecules at P, a distance r from S, oscillate with amplitude 8.0µm.
Point Q is situated a distance 2r from S.
What is the amplitude of oscillation of air molecules at Q?

Question 26, May 2008.
papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s08_qp_1.pdf
Click to expand...
Llamas said:
The intensity I of a sound at a point P is inversely proportional to the square of the distance x of P
from the source of the sound. That is
I ∝ 1/x^2
Air molecules at P, a distance r from S, oscillate with amplitude 8.0µm.
Point Q is situated a distance 2r from S.
What is the amplitude of oscillation of air molecules at Q?

May 2008, question 26.
Click to expand...
26)
I ¹/α x² so, doubling x means I would be divided by 4.
I α A² so, √(8²/4) = √16 = 4.0 μm

This can also be done like this :¬

I1/ I2 = A1² / A2²
1/(1/4) = 8² /x²
4/8² = 1/x²
x²= 16
x= √16
x= 4.0 μm
 
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