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Physics: Post your doubts here!

shikha95

shikha95

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Has anyone else noticed that in all pV=nRT, when converting from cm^3 to dm^3 , they multiply it to 10^-6 and not 10^-3. Can someone please explain that? ASAP! Thanks!
 
J

Jinosupreme

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shikha95 said:
Has anyone else noticed that in all pV=nRT, when converting from cm^3 to dm^3 , they multiply it to 10^-6 and not 10^-3. Can someone please explain that? ASAP! Thanks!
Click to expand...


It's not from cm^3 to dm^3. It is from cm^-3 to m^3, cause u are converting to SI unit, that's why is m^3.
 
snowbrood

snowbrood

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Musab100 said:
can anyone help me

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_12.pdf

MCQs :
2
16
17
18
27
30
34
36
38
Click to expand...
for question no 16
there are three forces acting on an object as it is lowered in an liquid. gravitational pull(downwards) upthrust(upwards) and viscous drag(upwards)
upthrust is the difference between the (pressure acting on the top of object)- (pressure acing on the bottom)
Viscous drag is the force that a solid experiences as it is lowered down the object due to its viscosity or density( we rather like to say viscosity when referred to a liquid).
since the object is stationary so no viscous drag. gravitional pull equals upthrust.

for q 17
C is the correct answers as
clockwise moment=anti clockwisemoment
(14*5)=(2*5)+(4*15). take the moment from pivot.

for q 18
2.1*9.81/cos65

for q27
young modulus = stress/strain
since we want ratio of x to y so lets consider x
2*youngmodulus =2*stress
area=pi*d^2/4
we have 2d in case of x so
area=pi*(0.5d)^2/4
area=(pi*d/16
this area is 1/4 of the area as in y

stress=force/area
2*stress=force/area*0.25
force=2*0.25=0.5
0.5:1
 
Suchal Riaz

Suchal Riaz

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Please read it:
In lecture i was taught things such as potential, electrical potential energy, drift velocity and much more. I didn't get anything.
At home i read coursebook, did test yourself question, end of chapter questions. Then i checked syllabus. Every point of syllabus had been covered in my private study that lasted a few days and i understood everything. I was happy that i had completed syllabus of electrocity but..
Now that i have open pacific physics and my lecture notes there are things which are not in coursebook or syllabus. Should i study them? Things such as drift velocity, electric potential energy, working of van der graaf etc despite the fact that they are not in syllabus?
 
shikha95

shikha95

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Suchal Riaz said:
Please read it:
In lecture i was taught things such as potential, electrical potential energy, drift velocity and much more. I didn't get anything.
At home i read coursebook, did test yourself question, end of chapter questions. Then i checked syllabus. Every point of syllabus had been covered in my private study that lasted a few days and i understood everything. I was happy that i had completed syllabus of electrocity but..
Now that i have open pacific physics and my lecture notes there are things which are not in coursebook or syllabus. Should i study them? Things such as drift velocity, electric potential energy, working of van der graaf etc despite the fact that they are not in syllabus?
Click to expand...

If it's not there in the syllabus, then there's no need to study it...unless you're done with everything and you're free, look through it. :)
 
Saad Mughal

Saad Mughal

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Suchal Riaz said:
Please read it:
In lecture i was taught things such as potential, electrical potential energy, drift velocity and much more. I didn't get anything.
At home i read coursebook, did test yourself question, end of chapter questions. Then i checked syllabus. Every point of syllabus had been covered in my private study that lasted a few days and i understood everything. I was happy that i had completed syllabus of electrocity but..
Now that i have open pacific physics and my lecture notes there are things which are not in coursebook or syllabus. Should i study them? Things such as drift velocity, electric potential energy, working of van der graaf etc despite the fact that they are not in syllabus?
Click to expand...
Pacific is an old book and is not according to our CIE A'level Physics syllabus so those you can leave those topics if they are not in the syllabus.
 
Lama AN

Lama AN

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Can someone explain for me the last part (b) ?? i ddnt get it .
its NOV\OCT 2008 V02 Q:2 part b
 
snowbrood

snowbrood

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periyasamy said:
Hai !This is a question from may june 2013 paper.Anyone can help me please?View attachment 32923
Click to expand...
some important points
the nucleus is initally at rest so its momentum is zero
mass of neutron is equal to proton(
mass of electrons is negligible
lets consider the mass of neutron or proton equal to n
A is neuclon number which is number of protons+neutrons
total number of protons+neutrons times the mass of one of them
total sum of momentum before decaying=after decaying

(nA)*0=n(A-1)u-(n*1)v .

signs change as they are moving in opposite direction
rearraging it gives n(A-1)u=nV
dividing each side with n gives
(A-1)u=V
 
periyasamy

periyasamy

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Hai ,can anyone help me to solve this doubt?Thanks a lot.Three question from may june 13.
 

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