The difference of pressure between two points along a horizontal pipe through which water is flowing is `14 cm` of `Hg`. If due to non-uniform cross section the speed of flow at a point of greater cross section is `60 cm//s`, speed of flow at the other point is

Options

A. `2m//s`
B. less than `60 cm//s`
C. not affected by non-uniform cross section
D. greater than `60 cm//s `

Answer

A, D

Explanation

According to Bernouli's equation
`P_(1)-P_(2)=1/2rho'v_(1)^(2)[((a_(1))/(a_(2))^(2))-1]`
`hrho=1/'2rho'V_(1)^(2)[((a_(1))/(a_(2))^(2))-1]`
where `rho` is density of mercury and `rhoox` is density of water Hence,
`1.4xx13.6xx980=1/2xxv_(1)^(2)[(v_(2)^(2))/(v_(1)^(2))-1]`
`:'a_(1)v_(1)=a_(2)v_(2)rho'=1`
`:' 2.8xx13.6x80+v_(1)^(2)=2.8xx13.6xx980x60^(2)`
Solving we get `v_(2)=202cm//s=2m//s`
`:.v_(2)gt60cm//s`