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Grade 12General Physics

Q29
Pls help with this sum i am having much difficulty

Question image for Q29 Pls help with this sum i am having much diffi
Profile image of Dx Jayden
6 Years agoGrade 12
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1 Answer

Profile image of Parth
ApprovedApproved Tutor Answer6 Years ago
see in this case you can not assume that flow at the radius R (i.e. at the top is negligible)
assume velocity at top = v1 and at orifice  = v2
using continuity and Bernoulli equation you’ve
pi*R^2*v1 = pi*r^2*v2
(v1^2)/2 + g*h ==(v2^2)/2  (rho is eliminated)
on solving you’ll find
v2 = 2^(1/2)*R^2*((g*h)/(R^4 - r^4))^(1/2)
then for flow rate pi*r^2*v2
then ans is 
2^(1/2)*R^2*r^2*pi*((g*h)/(R^4 - r^4))^(1/2)
option 2
pls approve