Fluid Mechanics mcq for Ph.D Entrance Exam - MECHANICAL ENGG [ IIT's ,BIT's NITs]

The variation in the volume of a liquid with the variation of pressure is called its

A. surface tension B. compressibility C. capillarity D. viscosity Answer & Explanation Answer: Option B

A point, in a compressible flow where the velocity of fluid is zero, is called

A. critical point B. vena contracta C. stagnation point D. none of these Answer & Explanation Answer: Option C

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 Answer & Explanation Answer: Option C

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 Answer & Explanation Answer: Option C

In case of flow through parallel pipes,

A. the head loss for all the pipes is same B. the total discharge is equal to the sum of discharges in the various pipes C. the total head loss is the sum of head losses in the various pipes D. Both (A) and (B) Answer & Explanation Answer: Option D

Coefficient of velocity is defined as the ratio of

A. actual velocity of jet at vena contracta to the theoretical velocity B. area of jet at vena contracta to the area of orifice C. actual discharge through an orifice to the theoretical discharge D. none of the above Answer & Explanation Answer: Option A

The magnitude of water hammer depends upon the

A. elastic properties of the pipe material B. elastic properties of the liquid flowing through the pipe C. speed at which the valve is closed D. all of the above Answer & Explanation Answer: Option D

Venturimeter is used to

A. measure the velocity of a flowing liquid B. measure the pressure of a flowing liquid C. measure the discharge of liquid flowing in a pipe D. measure the pressure difference of liquid flowing between two points in a pipe line Answer & Explanation Answer: Option C

The velocity of the liquid flowing through the divergent portion of a venturimeter

A. remains constant B. increases C. decreases D. depends upon mass of liquid Answer & Explanation Answer: Option C

The mercury does not wet the glass. This is due to the property of the liquid known as

A. cohesion B. adhesion C. viscosity D. surface tension Answer & Explanation Answer: Option D

According to Darcy's formula, the loss of head due to friction in the pipe is (where f = Darcy's coefficient, l = Length of pipe, v = Velocity of liquid in pipe, and d = Diameter of pipe)

A. B. C. D. Answer & Explanation Answer: Option D

The purpose of a surge tank is

A. to control the pressure variations due to rapid changes in the pipe line flow B. to eliminate water hammer possibilities C. to regulate flow of water to turbines by providing necessary retarding head of water D. all of the above Answer & Explanation Answer: Option D

The divergent portion of a venturimeter is made longer than convergent portion in order to

A. avoid the tendency of breaking away the stream of liquid B. to minimise frictional losses C. both (a) and (b) D. none of these Answer & Explanation Answer: Option C

A pitot tube is used to measure the

A. velocity of flow at the required point in a pipe B. pressure difference between two points in a pipe C. total pressure of liquid flowing in a pipe D. discharge through a pipe Answer & Explanation Answer: Option A

Bulk modulus of a fluid is the ratio of

A. shear stress to shear strain B. increase in volume to the viscosity of fluid C. increase in pressure to the volumetric strain D. critical velocity to the viscosity of fluid Answer & Explanation Answer: Option C

Coefficient of discharge Cd is equal to (where Cc = Coefficient of contraction, Cv = Coefficient of velocity, and Cr = Coefficient of resistance)

A. Cc x Cv B. Cc x Cr C. Cv x Cr D. Cc/Cr Answer & Explanation Answer: Option A

An orifice is said to be large, if

A. the size of orifice is large B. the velocity of flow is large C. the available head of liquid is more than 5 times the height of orifice D. the available head of liquid is less than 5 times the height of orifice Answer & Explanation Answer: Option D

When a liquid is flowing through a pipe, the velocity of the liquid is

A. maximum at the centre and minimum near the walls B. minimum at the centre and maximum near the walls C. zero at the centre and maximum near the walls D. maximum at the centre and zero near the walls Answer & Explanation Answer: Option A

The pressure of fluid due to hammer blow is

A. directly proportional to density of fluid B. inversely proportional to density of fluid C. directly proportional to (density)1/2 of fluid D. inversely proportional to (density)1/2 of fluid Answer & Explanation Answer: Option C