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Physics: Post your doubts here!

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Q22- Answer is a because it needs to have high sensitivity for small masses and low for high masses. The spring having smaller k stretches more and larger k stretches less. smaller k should be in the rigid box so it stretches till a certain extent. Hence small masses will make it stretch but when a large mass is present the small k spring will b stopped by the rigid box while the larger k will stretch less and show lower sensitivity.
Q7--> First of all the acceleration is negative because "g" which is acceleration due to gravity is negative and constant... The small pulse is as u know at the time the ball hits the ceiling... Imagine it like that: when it hits the ceiling and bounces back its acceleration increases...there is a simple concept to know that the answer is D, simply because the puls is approximately in the middle of the line... not towards the end as in C
Q15--> F=mg , and F=kv as mentioned in the question... so, mg=kv ....... so, v=(mg)/k
then you use KE=1/2 (m(v^2) ) and substitute v with (mg)/k.. u will get the expression in D
 
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Q5- x is 0.44. Add uncertainties. U get 0.03. (0.03/0.44)*100 = 7%
Q8- find speed in both places. speed between X and Y = 40/12 and speed between Y and Z is 40/6. Then acceleration = change in velocity/time. so find the change in velocity and divide it by the average of time i.e. (12+6)/2
Q14- find the hypotenuse force 1st. 200/sin30. that will give u 400N. Then 400*1.5 gives 600J. Add frictional force and u get 750J.
Q22- Answer is a because it needs to have high sensitivity for small masses and low for high masses. The spring having smaller k stretches more and larger k stretches less. smaller k should be in the rigid box so it stretches till a certain extent. Hence small masses will make it stretch but when a large mass is present the small k spring will b stopped by the rigid box while the larger k will stretch less and show lower sensitivity.
Q25 & 26- sorry i suck in this chap :/
Q33- answer is d as the current had to be 2 not 1.8. just add both resistance and divide voltage by it to fins current. for example for a resistance was 10. so 2+10=12. then V=IR so I=12/12=1
Q34- votage decreases linearly so its supposed to be b :)

Q8--> Can u please explain again? I think there is something wrong
Q14--> Why is the hypotenuse force 200/sin30, why not 200*sin30 ?
Q33--> Didn't get what u meant...
Q34--> What I thought was.. Lower resistivity means decreasing V.. I know that.. so, Why the answer is not D? Why the voltage decreases within th the material,? yes it shd decrease from the first one to the second... not through the first.. u got what I meant right?
Thanks for ur help but please clarify the above points..THANK YOU :)
 
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I've got quite a lot of problems. Would be extremely grateful if anyone could explain as much as they could.

O/N '10: P12 -- 22, 25, 27, 28
O/N '10: P11 -- 11, 34
O/N '09: P11 -- 10, 14, 15, 22, 28
M/J '09: P1 -- 9, 10, 11, 13, 15, 18

Sorry for any inconvenience in advance. :(
Requesting to be answered as soon as possible?

--Thank you, Oishee x
 
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Can anyone plz clarify how to find percentage uncertainty of May june 2012 variant 2 ????
i understood neither of the methods of MS
:cry:
 
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Yeah.. thnx.. but didnt get what u meant in Q27?
Can u also please do Nov 2010 P12 Q25 please?

27. What I meant was that Work Done on a point charge equals to the voltage x the charge. The charge for all the four is the same.
25. In tube X, the fundamental frequency will be 1/4 lambda. In tube Y, it'll be 1/2 lambda. f - 1/4, so x - 1/2.
 
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27. What I meant was that Work Done on a point charge equals to the voltage x the charge. The charge for all the four is the same.
25. In tube X, the fundamental frequency will be 1/4 lambda. In tube Y, it'll be 1/2 lambda. f - 1/4, so x - 1/2.

Ok.. got it Thanks a bunch :) :)
 
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Q 22 - 1st of all calculate mass* 6.02*10^23. this gives u the mass of all atoms in the crystal. then find the volume by dividing the mass u calculated by density. density=mass/volume. Then divide volume by 6.02*10^23. and find its cube root :)

Q25- Umm i guess extension will be the same as it obeys hookes law. Not sure though :/

Q26 - speed=2d/t. distance is muliplyd by 2 as its reflected so it travels the same distance twice. speed is that of light. so (2*150)/3*10^8 will give u 1 microsecond.

Q28- the two points are very apart by almost 1 full wave. Half wave apart is 180 degree but here the separation is greater so its 270.
Q35- sorry cant explain ! bad at this chap :/
Q38 - Just use a similar value for all resistors like 5ohm and calculate the combined resistance. If u use 5ohm then circuit 1 has resistance of 2ohm, 2 has 3 ohm. and 3 has 3.75 ohm :)

THANKS ALOT! :D
 
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the answer is A. This is beacuse pressure=hdg. so h=p/dg. pressure will now be 10% of atmospheric pressure. so (10/100)of atmospheric pressure. this gives atmospheric P/10 hence p/10dg :)
thnku so much sister for da help :)
 
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7. The component of acceleration is the acceleration due to gravity and that's the same always anywhere on Earth.
20. Choose a point and find the pressure due to P & Q at that same point. For example, any point on the second dotted line. The pressure due to Q will be = density of Q x g x h. The pressure due to P will be = density of Q x g x 2h. Cancel out g for both, you'll get density of Q = pressure/h, and density of P = pressure/2h.
25. Points on a wave vibrate up and down, and don't move to the right. A trough is travelling towards P, so P is going down.
 
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