Cavitation will begin when
The pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid
Pressure becomes more than critical pressure
Flow is increased
Pressure is increased
Correct Answer :
A. The pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid
Related Questions
Reynolds number is significant in
Supersonics, as with projectile and jet propulsion
Full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
Simultaneous motion through two fluids where there is a surface of discontinuity, gravity forces, and wave making effect, as with ship's hulls
All of the above
The divergent portion of a Venturimeter is made longer than convergent portion in order to
Avoid the tendency of breaking away the stream of liquid
To minimise frictional losses
Both (A) and (B)
None of these
Ratio of inertia force to surface Jension is known as
Mach number
Froude number
Reynoldss number
Weber's number
The force of buoyancy is always __________ the weight of the liquid displaced by the body.
Equal to
Less than
More than
None of these
The flow in a pipe or channel is said to be uniform when
The liquid particles at all sections have the same velocities
The liquid particles at different sections have different velocities
The quantity of liquid flowing per second is constant
Each liquid particle has a definite path
A uniform body 3 m long, 2 m wide and 1 m deep floats in water. If the depth of immersion is 0.6 m, then the weight of the body is
3.53 kN
33.3 kN
35.3 kN
None of these
A body floats in stable equilibrium
When its meatcentric height is zero
When the metacentre is above C.G.
When its e.g. is below its center of buoyancy
Metacentre has nothing to do with position of e.g. for determining stability
The viscosity of a liquid __________ its rate of flow through a hole in a vessel.
Effects
Does not effect
Both A and B
None of these
The hydraulic mean depth or the hydraulic radius is the ratio of
Area of flow and wetted perimeter
Wetted perimeter and diameter of pipe
Velocity of flow and area of flow
None of these
A piece of wood having weight 5 kg floats in water with 60% of its volume under the liquid. The specific gravity of wood is
0.83
0.6
0.4
0.3
A hemispherical tank of radius (R) has an orifice of cross-sectional area (a) at its bottom and is full of liquid. The time required to empty the tank completely is
14π R1/2/15Cd × a √(2g)
14π R3/2/15Cd × a √(2g)
14π R5/2/15Cd × a √(2g)
14π R7/2/15Cd × a √(2g)
A submerged body is said to be in a stable equilibrium, if its centre of gravity __________ the centre of buoyancy.
Coincides with
Lies below
Lies above
None of these
Specific weight of water in S.I. units is equal to
1000 N/m3
10000 N/m3
9.81 × 103 N/m3
9.81 × 10⁶ N/m3
Practical fluids
Are viscous
Possess surface tension
Are compressible
Possess all the above properties
A flow through a long pipe at decreasing rate is called __________ uniform flow.
Steady
Unsteady
Both A and B
None of these
The discharge through a large rectangular orifice is given by (where H1 = Height of the liquid above the top of the orifice, H2 = Height of the liquid above the bottom of the orifice, b = Breadth of the orifice, and Cd = Coefficient of discharge)
Q = (2/3) Cd × b × √(2g) × (H2 - H1)
Q = (2/3) Cd × b × √(2g) × (H2 1/2 - H1 1/2)
Q = (2/3) Cd × b × √(2g) × (H2 3/2 - H1 3/2)
Q = (2/3) Cd × b × √(2g) × (H2 2 - H1 2)
A flow in which the volume of a fluid and its density does not change during the flow is called _________ flow.
Incompressible
Compressible
Viscous
None of these
In case of flow through parallel pipes,
The head loss for all the pipes is same
The total discharge is equal to the sum of discharges in the various pipes
The total head loss is the sum of head losses in the various pipes
Both (A) and (B)
The bulk modulus of elasticity
Has the dimensions of 1/pressure
Increases with pressure
Is large when fluid is more compressible
Is independent of pressure and viscosity
The unit of kinematic viscosity in S. I. units is
N-m/s
N-s/m2
m2/s
N-m
The most economical section of a rectangular channel is one which has hydraulic mean depth or hydraulic radius equal to
Half the depth
Half the breadth
Twice the depth
Twice the breadth
Froude number is significant in
Supersonics, as with projectile and jet propulsion
Full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
Simultaneous motion through two fluids where there is a surface of discontinuity, gravity forces, and wave making effect as with ship's hulls
All of the above
The property of a liquid which offers resistance to the movement of one layer of liquid over another adjacent layer of liquid, is called
Surface tension
Compressibility
Capillarity
Viscosity
Mercury does not wet glass. This is due to property of liquid known as
Adhesion
Cohesion
Surface tension
Viscosity
In an immersed body, centre of pressure is
At the centre of gravity
Above the centre of gravity
Below be centre of gravity
Could be above or below e.g. depending on density of body and liquid
The total pressure on a horizontally immersed surface is (where w = Specific weight of the liquid, A = Area of the immersed surface, and x = Depth of the centre of gravity of the immersed surface from the liquid surface)
wA
wx
wAx
wA/x
The length AB of a pipe ABC in which the liquid is flowing has diameter (d1) and is suddenly contracted to diameter (d2) at B which is constant for the length BC. The loss of head due to sudden contraction, assuming coefficient of contraction as 0.62, is
v₁²/2g
v₂²/2g
0.5 v₁²/2g
0.375 v₂²/2g
The increase of temperature results in
Increase in viscosity of gas
Increase in viscosity of liquid
Decrease in viscosity of gas
Decrease in viscosity of liquid
According to Manning's formula, the discharge through an open channel is (where M = Manning's constant)
A × M × m1/2 × i2/3
A × M × m2/3 × i1/2
A1/2 × M2/3 × m × i
A2/3 × M1/3 × m × i
The viscosity of water is __________ than that of mercury.
Higher
Lower
Same as
None of these