Question

A horizontal tube of uniform cross-sectional area `A` is bent in the form of `U` as shown in figure. If the liquid of density `rho` enters and leaves the tube with velcity v, then the extermal force `F` requried to hold the bend stationary is

A. `F=0`
B. `rhoAv^(2)`
C. `2rhoAv^(2)`
D. `(1)/(2) rhoAv^(2)`

Answer 1

Correct Answer - C
`F=(Delta p)/(Delta t)=((Delta m)/(Delta t))(Delta v)`
`=rho((Delta V)/(Delta t))(2v)`
`=(rho)(Av)(2v)=2rhoAv^(2)`.