a) Both A and R are true and R is the correct explanation of A
b) Both A and R are true but R is not a correct explanation of A
c) A is true but R is false
d) A is false but R is true
421. Assertion A : At the critical state of flow, the specific force is a minimum for the given discharge.
Reason R :For a minimum value of the specific force, the first derivative of force
with respect to depth should be unity
422. Assertion A : The Specific speed of a Pelton wheel is generally much less than
that of a reaction turbine.
Reason R : Pelton wheels generally use more than one nozzle and the specific
speed is defined for power developed per nozzle. b
423. Assertion A : Pressure intensity in a liquid flow is a form of energy.
Reason R : The pressure gradient is a measure of the rate of energy dissipation
in steady uniform flow. b
424. Assertion A : The following potential function in two-dimensional flow field
represents rotational flow Φ = 2x² - 3y² Reason R : For the given function
425. Assertion A : In Rayleigh's method of dimensional analysis, the dependent variable is written as the function of exponential terms of independent variables.
Reason R : In Rayliegh's method, when the number of independent variable
exceeds three, the exponents of non repeating variables are expressed as the
exponents of repeating variables. b
426. Assertion A : If laminar flow of oil between two points of a given pipeline is
doubled, then the power consumption is increased to four times the original power.
Reason R : In laminar flow through circular pipes, head loss varies directly as
the discharge a
427 Assertion A : In the equation
for laminar flow through the pipe, the term v (mean velocity of flow) is given by
Reason R : The term T (friction factor) in the above equation equals 64/Re , where
428. Assertion A : Water flows through a pipe connecting two reservoirs. The line
joining the water surface levels in the reservoirs is the hydraulic gradient
Reason R : There will be no negative gauge pressure anywhere in the pipeline,
as long as the pipeline lies below the hydraulic gradient. b
429. Assertion A : Irrotational flow exists when the net rotation of the fluid about
its mass centre is zero.
Reason R: There is always a possibility of rotation in ideal fluid and therefore, ideal fluids cannot have irrotational flow.
430. Assertion A : The inlet velocity triangle for a Pelton turbine is a straight line
Reason R : For a Pelton turbine, the vane angle at inlet is 180° a
431. Assertion A : A minor change in specific energy at or close to critical state
will cause a major change in depth.
Reason R: A critical state of flow is characterized by its Froude number being
equal to unity. b
432. Assertion A : The movement of two blocks of wood wetted with hot glue
requires greater and greater effort as the glue is drying up.
Reason R : Viscosity of liquids varies inversely with temperature
433. Assertion A : There is no flow in the direction perpendicular to a stream line at
any point on it.
Reason R : Stream line consists of a number of infinitesimally small segments
such that all of them lie along the directions of velocity vectors of fluid
particles at those segments
434. Assertion A : Continuity equation must hold good in a pipe network system.
Reason R : In a pipe network analysis, the flow into any junction must be equal
to the flow out of the junction. a
435. Assertion A : Water hammer occurs when the quick-acting valve at the end of a long pipeline is suddenly closed.
Reason R : Surge tanks are provided in penstocks to relieve the penstock of high
water hammer pressure when the flow into a turbine is stopped due to low power
436. Assertion A : In the standing-wave flume, flow occurs in a super-critical state
so that discharge can be related to a depth upstream of flow
Reason R : A standing wave flume is a venturi flume operating under one
condition in which a hydraulic jump is formed. d
437.Assertion A : The discharge (Q) through a triangular weir is given by
where Cd is the coefficient of discharge, h is the head of flow, 6 is the apex angle
of the weir and g is the acceleration due to gravity.
Reason R : The cross-sectional area of flow in a triangular weir is h2 tan (9/2) and
average velocity is
438. Assertion A : When both gravitational and viscous forces are predominant in a flow scale ratio can be chosen at will.
Reason R : With both gravitational and viscous forces being predominant, scale
ratio depends upon kinematic viscosity of the fluids. d
439. Assertion A : Any discharge will flow as critical in a wide rectangular channel
whose bed slope is 1 in C²/g
Reason R :The critical depth of flow through a wide rectangular channel is (q²/g)¹/³ a
440. Assertion A : Loss of head at a sudden expansion in a pipe is greater
than that at a sudden contraction.
Reason R : Flow in a sudden expansion tends to be irrotational. c
441. Assertion A : The kinematic viscosity of both air and water decreases as the
Reason R : The kinematic viscosity of liquids and gases at a given pressure is a
function of temperature d
442. Assertion A : Energy is lost in sudden contraction in a pipeline.
Reason R : If the flow is now reversed, energy can be gained at the transition which acts as an expansion c