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Physics: Post your doubts here!

rz123

rz123

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Unicorn said:
ok same paper question 15
Click to expand...
oh i was kidding u took my word serious :p
anyway what i get is dat if u c in both vessels the height will decrease by half from the original height in the vessel X, means h will bcm h/4 altogether, so the answer will be B mgh/4.
 
princesszahra

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Rvel Zahid said:
oooww which one r u solving princess of Mars, i asked for the momentum question. i m done with it. lazy of me to not c the notes. it says dat relative speed of approach equals to relative speed of separation so its D. hope ur doubt is clear. :D
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huH!! i solved the first one!!:p
i thought how duffer of u not to get that right!HEHEHEEE !!
 
rz123

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princesszahra said:
huH!! i solved the first one!!:p
i thought how duffer of u not to get that right!HEHEHEEE !!
Click to expand...
no u didn't. how much duffer of me? quantity and SI unit required!!!
yes dat was a piece of cake. sometimes even gr8 scientists cannot get a simple thing.:p
 
rz123

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Which type of radiation will produce fringes which are the closest together? [1]
A blue light
B infrared radiation
C red light
D ultraviolet radiation
 
rz123

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In a resonance-tube experiment, a tuning fork vibrating at
a frequency of 256 Hz is held over the open end of a tube
(as shown in the diagram).
A stationary wave can form in the air between the open end of
the tube and the surface of the water. The antinode at the open
end of the tube does not occur exactly at the end but at a small
distance c from this end. The distance c is known as the ‘endcorrection’.
The value of c for a particular tube does not
depend on the harmonic.
This experiment takes into account any errors that may occur
due to the end-correction. The tube is fully immersed into the
water. The open end of the tube is slowly raised. A loud
sound is first heard when the top of the tube is 30 cm above
the surface of the water. The next loud sound is heard when
the top of the tube is 95 cm above the water surface.
Use this information to determine the speed of sound in air.
 
rz123

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Muhammad Talha said:
http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_s09_qp_1.pdf
Plz solve these ques:
2,13,14,15,18,20,21,25,33....
Plz reply asap.....:)
Click to expand...
hi, this is my try:-

2) in this mcq you are given with the angle and horizontal component.use it to find the vertical comp.
Tan30 = Perpendicular / 20 , it comes 11.5N i.e C.

13) no convincing ans but the weight is making a torque of 180 Nm, how? 900 N into .20m (.20 is the perpendicular distance or the radius of the disc)
same torque will be shifted upwards in order to lift this weight i.e 180 = F into 1.20 m it comes 150 N hence B. ( i dnt knw why i took .20 as the perp distance to find the torque created by weight)

14) Power = F v , so k = P over v^3 because you need to add another v in the denominator as F = Power over velocity.

15) what i get is dat if u c in both vessels the height will decrease by half from the original height in the vessel X, means h will bcm h/4 altogether, so the answer will be B mgh/4.

18) pressure = pgh , p ang remain constant. u know that h has increased in the right side of manometer. i.e pressure has increased. there is only option D 2pgh which supports this idea. other three options shows decrease or no change in the pressure.

20) extension directly proportional to length and inversely proportional to area. length is twice so this increase the extension by 2, area has decreased as well by half so this also doubles the extension, total extension raised by 4 times. the ratio of the tension will be 4 /1. (not so clear i know)

21) strain energy = 1/2 F into x so 1/2 into 17 into 30 /100 it comes around 2.5 J but the best estimate would be less then that i.e 2 Joules which is nearest to the whole number. 3J would be very higher i.e A option

25)i dnt understand :mad: , it shud be C but its A, d sin Q = n lambda , this s what comes after moving here nd dre things
n/N = sin Q / Lambda

33) U must see that the two cells are not in one direction, cancelling each others voltage. i.e subtract these two 3V- 1.2 V = 1.8 Volt , now use this to find the current in loop 1 which has 9 ohm resistor. I = 1.8 / 9 = .20 Ampere i.e B.
 
zain786

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can anyone plz upload the answers to these....thnx
 

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zain786

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Rvel Zahid said:
answers to the all questions? i don't think that will be feasible. if any specific question then tell me.
Click to expand...
bro ther must be some1 whose done em all....anywayz thnx for lookng...the qs i need help in...are:
3, 4, 5, 6
 
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Mustehssun Iqbal said:
Assalamu alaikum,
http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_w08_qp_1.pdf
Q.4,12, 33 and 36. Thanks in advance!
Click to expand...
q.4 tasty! readings between. 1.98A to 2.02A involves 4 values or 4 readings in total. so the uncertainty for one reading is .01, so total uncertainty will be .04. u will write as 2.00 +- .04.

12) u know that friction always opposes the motion, i.e upwards in this case as the object is travelling downwards. resultant force is zero as all forces are balanced that's why the object is moving with CONSTANT velocity.

33) its a fact. we must see the book for the I/V diagrams for thermistor, lamp, semiconductor and a metal wire. as the temperature increases the resistance increases as well. I = V/R current and voltage are inversely proportional to the resistance.

36) you need to calculate internal resistance first. you are given with the terminal voltage (i assume u know this term) make two equations by keeping in MIND that current is same. I = 1.5 / R1 ( r1 is the internal resistance and 1.5 is the voltage used by the internal resistance as 9-7.5 = 1.5 wohoo !!!!! ) 2nd equation is I = 9 / 15 + R1 , now equate both equations and you will get R1 to be 3 Oooohmzs! I = 9 / 18 = .50 Ampere or you could have simply divided the 7.5 by 15 to find the current in the circuit. as 7.5 is the voltage used by the resistor excluding the resistance used by the battery. but i told you the previous method for similar questions...
 
rz123

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zain786 said:
bro ther must be some1 whose done em all....anywayz thnx for lookng...the qs i need help in...are:
3, 4, 5, 6
Click to expand...
i highly doubt dat, if u somehow find the marking scheme then kindly upload.
for 3: homogeneity test of equations: means the base units on both side of the equations should be same not taking the numerical values on the both side into consideration. i.e v= m/s , now any option after passing this test equal to m/s then that equation is correct. apply to A, underoot ms^-2 into m this will eventually equal to m/s. hence A option is correct.

4) i think its B, as the human reaction error must be about .2 seconds thats why delay on the time axis (not sure)

5) C ? :/ , as V = 3% error multiplied by two , R is 2% error total 8 % error. i dnt remember exactly but there is a way to do this like the power goes down with V we need multiply by 2 the error.....

6) its D, the resultant will originate from the same point as the other 3 forces, now the resultant is springing outwards, we can't show dat on a 2D paper, so it will be D as resultant can't be into the plane or downwards u know..
 
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