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ALL CIE PHYSICS DOUBTS HERE !!!

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$!$RatJumper$!$:
Thank you for that. It was really useful!
Though i have a doubt, the equation is:
Change in K.E + Useful work done = Total k.E in overcoming friction + Change in P.E

Why didnt you use the Change in K.E in this calculation?

ashish:

--- Quote from: thecandydoll on November 13, 2010, 07:02:25 am ---Oct/Nov 2004. MCQ Q20.
q18

--- End quote ---

Q20

Pressurep at depth 2x= atm+2xDPg

on the right arm  pressure         =atm+xDQg

they are at equilibrium
 atm+2xDPg = atm+ xDQg
simplifying on both side you get
2DP= DQ
DP/DQ= 1/2

note D = density

Hypernova:

--- Quote from: $!$RatJumper$!$ on November 13, 2010, 08:48:14 am ---Thank you for that. It was really useful!
Though i have a doubt, the equation is:
Change in K.E + Useful work done = Total k.E in overcoming friction + Change in P.E

Why didnt you use the Change in K.E in this calculation?

--- End quote ---

Change in KE is zero, since no chnage in velocity

using your equation

0+9000x40 = Work done by friction + 20000x12

its the same thing

$!$RatJumper$!$:

--- Quote from: Hypernova on November 13, 2010, 08:54:09 am ---Change in KE is zero, since no chnage in velocity

using your equation

0+9000x40 = Work done by friction + 20000x12

its the same thing


--- End quote ---

Thanks :)


--- Quote from: ashish on November 13, 2010, 08:50:56 am ---Q20

Pressurep at depth 2x= atm+2xDPg

on the right arm  pressure         =atm+xDQg

they are at equilibrium
 atm+2xDPg = atm+ xDQg
simplifying on both side you get
2DP= DQ
DP/DQ= 1/2

note D = density


--- End quote ---

Please explain this equation u used. We have not been taught it before.. :(
Thank you

ashish:

--- Quote from: $!$RatJumper$!$ on November 13, 2010, 08:56:55 am ---Thanks :)

Please explain this equation u used. We have not been taught it before.. :(
Thank you

--- End quote ---

pressure in a liquid = h(rho)g
row means density which i represented by D
h=height

pressure at the same level(height) in a liquid is equal

pressure in left arm at a depth of 2x = atmospheric pressure (atm) + pressure by liquid
                                                  = atm + 2xDpg

pressure in the right arm (in the diagram the liquid has height x) = atm + xDQg

since pressure in a liquid i at same level(height) is equal

atm + 2xDpg = atm + xDQg

Dp= density of liquid P
DQ= density of liquid Q

hope it helps



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