Q.

A non-viscous fluid of density ρ is flowing in a tube as shown in figure. Area of section-(1) is double that of section-(2). Centre of mass of section-(2) is h height above the Centre of mass of section-(1) and level of water in tube-1 is 'h' height above that in tube-2. Then:

1 Velocity of fluid of section-(1) is gh3  
2 Velocity of fluid at section-(1) is 2gh3  
3 Work done by gravitational force per unit volume from section-(1) to section-(2) is ρgh   
4 Work done by elastic forces (pressure) per unit volume from section-(1) to section-(2) is 3ρgh  

Ans.

(2)

Applying Bernoulli's equation from section-(1) and (2)

P1+12ρV12+ρgh1=P2+12ρV22+ρgh2

P1+12ρV2+0=P2+12ρ(2V)2+ρgh

and  P1-P2=ρg(2h)

Solving we get,  V=2gh3

(C) Work done by gravitation force per unit value Wg=decrease in gravitational

       PTvalue=ρgh1-ρg2

       PTvalue=ρgh1-ρgh2

       Wgr=0-ρgh

(D) Work done by elastic force volume, We=decrease in elastic P.E vol=decrease in pressure

       Evol=P1-P2=ρG(2h)