## Fluid Mechanics Water hammer is caused, when water flowing in a pipe is suddenly brought to rest by closing the valve. The extent of pressure thus produced due to water hammer depends on the

Pipe length
Fluid velocity in the pipe
All of these
Time taken to close the valve

## Fluid Mechanics Pressure drag does not depend upon the

Roughness of surface of the body
Length of the body in flow direction
Pressure of main flow only
All of these

## Fluid Mechanics The bulk modulus of elasticity of a liquid

Decreases with pressure
Is zero for incompressible liquid
Is independent of temperature & pressure
Increases with pressure

## Fluid Mechanics For turbulent fluid flow in pipe, the expression for Prandtl one seventh power law is (where, r = pipe radius, x = distance).

None of these
V/Vmax = (x.r)1/7
V/Vmax = (x/r)1/7
V/Vmax = (r/x)1/7

Δp²
Δp/2
2Δp
Δp

## Fluid Mechanics Prandtl mixing length is

None of these
Applicable to laminar flow problems
A universal constant
Zero at the pipe wall