A. The absolute roughness of a pipe de-creases with time
B. A pipe becomes smooth after using for long time
C. The friction factor decreases with time
D. The absolute roughness increases with time
Related Mcqs:
- Select the incorrect statement?
A. The pressure intensity at vena contracta is atmospheric
B. Contraction is least at vena contracta
C. Stream lines are parallel throughout the jet at vena contracta
D. Coefficient of contraction is always less than one - Which of the following statements is correct ?
A. Lower critical Reynolds number is of no practical significance in pipe flow problems.
B. Upper critical Reynolds number is significant in pipe flow problems.
C. Lower critical Reynolds number has the value 2000 in pipe flow
D. Upper critical Reynolds number is the number at which turbulent flow changes to laminar flow - The correct relationship among displacement thickness d, momentum thickness m and energy thickness e is_________________?
A. d > m > e
B. d > e > m
C. e > m > d
D. e > d > m - Which of the following is an incorrect statement ?
A. Coefficient of contraction of a venturimeter is unity
B. Flow nozzle is cheaper than venturimeter but has higher energy loss
C. Discharge is independent of orientation of venturimeter whether it is horizontal, vertical or inclined
D. None of the above statement is correct. - Centre of buoyancy always_________________?
A. coincides with the centre of gravity
B. coincides with the centroid of the volume of fluid displaced
C. remains above the centre of gravity
D. remains below the centre of gravity - The discharge through a V- notch varies as______________?
A. H1/2
B. H3’2
C. H5/2
D. H5’4 where H is head - In which of the following the friction drag is generally larger than pressure drag?
A. a circular disc or plate held normal to flow
B. a sphere
C. a cylinder
D. an airfoil - The speed of a pressure wave through a pipe depends upon________________?
A. the length of pipe
B. the viscosity of fluid
C. the bulk modulus for the fluid
D. the original head - If x is the distance from leading edge, then the boundary layer thickness in laminar flow varies as________________?
A. x
B. x
C. x
D. x/7 - The viscosity of a gas_______________?
A. decreases with increase in temperature
B. increases with increase in temperature
C. is independent of temperature
D. is independent of pressure for very high pressure intensities
