# Fluid Mechanics 16

Mechanical Engineering MCQ Question Papers: DRDO, ISRO, Interview

Subject: Fluid Mechanics 16

Part 4: List for questions and answers of Fluid Mechanics

Q1. Shear stress in a turbulent flow is given by the formula τ = η (du / dy) Where η (eta) is,
a) Eddy viscosity
b) Apparent viscosity
c) Virtual viscosity
d) All of the above

Q2. What is the ratio of maximum velocity to average velocity, when the fluid is passing through two parallel plates and flow is laminar?
a) 3/2
b) 2/3
c) 4/3
d) 3/4

Q3. Coefficient of friction for laminar flow is given as Where, Re = Reynold’s number
a) (Re / 32)
b) (32 / Re)
c) (Re / 16)
d) (16 / Re)

Q4. How should be the viscosity of the flowing fluid for laminar flow?
a) Viscosity of the fluid should be as low as possible, for laminar flow
b) Viscosity of the fluid should be as high as possible, for laminar flow
c) Change in viscosity of the flowing fluid does not affect its flow
d) Unpredictable

Q5. The flow of fluid will be laminar when,
a) Reynold’s number is less than 2000
b) The density of the fluid is low
c) Both a and b
d) None of the above

Q6. When a tank containing liquid moves with an acceleration in the horizontal direction,
then the free surface of the liquid
a) Remains horizontal
b) Becomes curved
c) Falls on the front end
d) Falls on the back end

Q7.A pressure of 25 m of head of water is equal to
a) 25 kn/ m^2
b) 245 kn/ m^2
c) 2500 kn/m^2
d) 2.5 kn/ m^2

Q8. The hammer blow in pipes occurs when
a) There is excessive leakage in the pipe
b) The pipe bursts under high pressure of fluid
c) The flow of fluid through the pipe is suddenly brought to rest by closing of the valve
d) The flow of fluid through the pipe is gradually brought to rest by closing of the valve

Q9. The resultant upward pressure of the fluid on an immersed body is called
a) Up-thrust
b) Buoyancy
c) Center of pressure
d) All the above are correct

Q10. When the water level on the downstream side of a weir is above the top surface of a weir, the weir is known as
a) Narrow-crested weir
c) Ogee weir
d) Submerged weir

Q11. If the surface of liquid is convex, men
a) Cohesion pressure is negligible
b) Cohesion pressure is decreased
c) Cohesion pressure is increased
d) There is no cohesion pressure

Q12. The atmospheric pressure with rise in altitude decreases
a) Linearly
b) First slowly and then steeply
c) First steeply and then gradually
d) Unpredictable

Q13. Dynamic viscosity of most of the gases with rise in temperature
a) Increases
b) Decreases
c) Remain unaffected
d) Unpredictable

Q14. Center of buoyancy is the
a) Centroid of the displaced volume of fluid
b) Center of pressure of displaced volume
c) Does not exist
d) None of the above

Q15. When a body is placed over a liquid, it will sink down if
a) Gravitational force is equal to the up-thrust of the liquid
b) Gravitational force is less than the up-thrust of the liquid
c) Gravitational force is more than the up-thrust of the liquid
d) None of the above

Q16. The property by virtue of which a liquid opposes relative motion between its different layers is called
a) Surface tension
b) Coefficient of viscosity
c) Viscosity
d) Osmosis

Q17. A weir is said to be narrow-crested weir, if the width of the crest of the weir is__________ half the height of
a) Water above the weir crest
b) Equal to
c) Less than
d) More than

Q18. Euler’s dimensionless number relates the following
a) Inertial force and gravity
b) Viscous force and inertial force
c) Viscous force and buoyancy force
d) Pressure force and inertial force

Q19. When a body floating in a liquid, is displaced slightly, it oscillates about
a) C.G. of body
b) Center of pressure
c) Center of buoyancy
d) Metacentre

Q20. The pressure of the liquid flowing through the divergent portion of a Venturimeter
a) Remains constant
b) Increases
c) Decreases
d) Depends upon mass of liquid

Part 4: List for questions and answers of Fluid Mechanics