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ALL CIE PHYSICS DOUBTS HERE !!!

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ashish:

--- Quote from: thecandydoll on November 14, 2010, 03:34:43 am ---may/june 2009
20/21

I dont get it :(

--- End quote ---

no.20

young modulus will be constant in the same material
Y=young modulus=Stress/strain

Y=Fl/eA
Yp=Fpl/eA

YQ=FQ2l/e(A/2)
                   = 4FQl/eA

YQ=Yp
4FQl/eA=Fpl/eA
eliminating l,e and A
you will get

4FQ= Fp
Fp/Q= 4/1

ashish:

--- Quote from: thecandydoll on November 14, 2010, 03:59:25 am ---wrong questions.

http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w09_qp_11.pdf


Q15

--- End quote ---

1st by law of conservation of momentum
m1v1=M2v2
2*2=1*v2
v2=4

kinetic energy of the two trolley = (0.5*2*22)+ 0.5*16
                                   =4+8
                                    =12

ashish:

--- Quote from: thecandydoll on November 14, 2010, 03:34:43 am ---may/june 2009
20/21

I dont get it :(

--- End quote ---

21) divide the graph into 2 trapeziums(0-20)and (20-30)

=((0.5*(20+10)*5)+ (0.5*(5+17)*10))/100
=1.85 + almost 6 squares out of the graph
=1.91
~ 2.0 A(approximation)

ashish:

--- Quote from: $!$RatJumper$!$ on November 13, 2010, 11:26:00 pm ---S08 Q 24, 29, 32, 34 please
:)

--- End quote ---

24) directly C because for same materials young modulus is constant

32)
P=I2R
Px=I2R
R=Px/I2

Py= (I/2)22R
Py=I2R/2
R=2Py/I2

equating both you will get
Px=2Py

Py/Px= 1/2



34)rho will be constant in both wire

V=Ay*4L
V=Ax*L

equating both you will get
Ax =4Ay------(1)

R= (rho)L/A
rho=RA/L

for wire x
rho= Rx * Ax / L

for wire Y

rho = Ry * Ay /4L

equating both

Ry * Ay /4L = Rx * Ax / L

from 1 Ax =4Ay

now substitute in the equation

AyRy/4L = 4 AyRx/L

after simplifying
Ry=16Rx
Ry/Rx=16

$!$RatJumper$!$:

--- Quote from: ashish on November 14, 2010, 04:55:43 am ---24) directly C because for same materials young modulus is constant

32)
P=I2R
Px=I2R
R=Px/I2

Py= (I/2)22R
Py=I2R/2
R=2Py/I2

equating both you will get
Px=2Py

Py/Px= 1/2



34)rho will be constant in both wire

V=Ay*4L
V=Ax*L

equating both you will get
Ax =4Ay------(1)

R= (rho)L/A
rho=RA/L

for wire x
rho= Rx * Ax / L

for wire Y

rho = Ry * Ay /4L

equating both

Ry * Ay /4L = Rx * Ax / L

from 1 Ax =4Ay

now substitute in the equation

AyRy/4L = 4 AyRx/L

after simplifying
Ry=16Rx
Ry/Rx=16

--- End quote ---

Thank you :)

Though could you please explain Q24 in terms of E = pL/Ae ? Like for instance by doubling L wouldn't we double E because they are proportional in the equation?
I get that the modulus doesn't change, but in terms of doubling and stuff, could you please explain :)

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