This is a good one:
This is a capillary with a difference : it is two coaxial cylinders of radius 'a' and 'b', with a < b..
The inner cylinder is solid while the outer, obviously, is hollow..
When this capillary is put into water of surface tension 'T' and contact angle 0..predict the height rise in the capillary.
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ReplyDeletespeed.. man!itna aasaan tha kya yaar??
ReplyDeleteyaar, I'm getting H = 4T/g(b-a)
ReplyDeleteThis comment has been removed by the author.
ReplyDeletelook,
ReplyDeleteHg=2T/r rho=1, r is the radius
now, r=(b-a)/2
and now he's on 199 with dhoni on strike...
na..r=b-a/2???
ReplyDeletei won't be so sure...
kkkk, i got it ...
ReplyDeleteThis comment has been removed by the author.
ReplyDeletei removdd my post as i hd put solutn in that n saw that bhaiya has deleted my post in order to keep the answer secret.
ReplyDeletegud thot.
is the answer 2T/g(b^2-a^2)^1/2
ReplyDeleteno arun.
ReplyDeletemera to rise ki jagah fall aa rha hai!
ReplyDeleteit should be 2T/(b-a)(rho)g
ReplyDeleteya..anyone with the soln. now..
ReplyDeletefirst i tried wid the thing given in module (take perpendicular radii....) but i cud nt do it
ReplyDeletethen i equated forces
2(pi)T(a+b) + P(pi)(b^2-a^2) = p-atm (pi)(b^2-a^2)
got delta p as 2T /(b-a)
then the normal pressure conservation.
is the ans 2Tb/g(b^2-a^2)
ReplyDeletesurface tension X change in area = surface energy
ReplyDeleteT(2)(pi)(b+a)h = (h^2)(b^2-a^2)(pi)(rho)g
h=2T/(rho)g(b-a)
sir please give explanation of QUESTION of MOI OF HEMISPHERE ABOUT DIFFERENT AXIS POSTED by you
ReplyDeletesir please give explanation of QUESTION of MOI OF HEMISPHERE ABOUT DIFFERENT AXIS POSTED by you
ReplyDeleteitna karne ki zarurat hi nhi.
ReplyDeleter in the formula fr capillary rise of h is radial distance available to get filled up.
in normal cases its radius of capillary.
in this case its b-a.
thats it.
yar mera to ans 2 times a rha hai..
ReplyDeletei am getting radius of capillary as (b-a)/2
b-a cappilary ki width nhi hai jahan paani bhar rha hai? so its radius is b-a/2..
where am i going wrong?
H= (2T)/(b-a)pg
ReplyDeletep=rho
A child of mass m sits in a swing of negligible mass suspended by a rope of length l. Assume that the dimensions of the child are negligible compared with l.
ReplyDeleteHis father pulls the child back until the rope makes an angle of one radian with vertical, then pushes with a force F=mg along the arc of the circle releasing at the vertical :
a) How high up will the swing go?
b) How long did the father push?