Free surface of a liquid tends to contract to the smallest possible area due to force of
Surface tension
Viscosity
Friction
Cohesion
Correct Answer :
A. Surface tension
Related Questions
The horizontal component of buoyant force is
Negligible
Same as buoyant force
Zero
None of the above
The unit of viscosity is
Metres² per sec
kg-sec/metre
Newton-sec per metre²
Newton-sec per meter
An internal mouthpiece is said to be running __________ if the length of the mouthpiece is more than three times the diameter of the orifice.
Free
Partially
Full
None of these
Uniform flow occurs when
The flow is steady
The flow is streamline
Size and shape of the cross section in a particular length remain constant
Size and cross section change uniformly along length
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
The total pressure on the top of a closed cylindrical vessel of radius (r) completely filled up with liquid of specific weight (w) and rotating at (ω) rad/s about its vertical axis, is
π w ω² r²/4g
π w ω² r³/4g
π w ω² r⁴/4g
π w ω² r²/2g
The discharge through a channel of trapezoidal section is maximum when
Width of channel at the top is equal to twice the width at the bottom
Depth of channel is equal to the width at the bottom
The sloping side is equal to half the width at the top
The sloping side is equal to the width at the bottom
Which of the following instruments is used to measure flow on the application of Bernoulli's theorem?
Venturimeter
Orifice plate
Nozzle
All of the above
A flow in which each liquid particle has a definite path, and the paths of individual particles do not cross each other, is called
Steady flow
Uniform flow
Streamline flow
Turbulent flow
All the terms of energy in Bernoulli's equation have dimension of
Energy
Work
Mass
Length
The units of dynamic or absolute viscosity are
Metres² per sec
kg sec/meter
Newton-sec per meter
Newton-sec² per meter
The height of a water column equivalent to a pressure of 0.15 MPa is
15.3 m
25.3 m
35.3 m
45.3 m
The product of mass and acceleration of flowing liquid is called
Inertia force
Viscous force
Gravity force
Pressure force
A flow whose streamline is represented by a straight line, is called __________ dimensional flow.
One
Two
Three
Four
When the flow parameters at any given instant remain same at every point, then flow is said to be
Quasi-static
Steady state
Laminar
Uniform
Mercury is often used in barometer because
It is the best liquid
The height of barometer will be less
Its vapour pressure is so low that it may be neglected
Both (B) and (C)
The theoretical velocity of jet at vena contracta is (where H = Head of water at vena contracta)
2gH
H × √(2g)
2g × √H
√(2gh)
A model of torpedo is tested in a towing tank at a velocity of 25 m/sec. The prototype is expected to attain a velocity of 5 m/sec. What model scale has been used?
1 : 5
1 : 2.5
1 : 25
1 : √5
For measuring flow by a Venturimeter, if should be installed in
Vertical line
Horizontal line
Inclined line with flow downward
In any direction and in any location
A weir is said to be broad crested weir, if the width of the crest of the weir is ________ half the height of water above the weir crest.
Equal to
Less than
More than
None of these
A jet of water discharging from a 40 mm diameter orifice has a diameter of 32 mm at its vena contracta. The coefficient of contraction is
0.46
0.64
0.78
0.87
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)
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
The pressure at a point in a fluid will not be same in all the directions when the fluid is
Moving
Viscous
Viscous and static
Viscous and moving
One cubic metre of water weighs
100 litres
250 litres
500 litres
1000 litres
If cohesion between molecules of a fluid is greater than adhesion between fluid and glass, then the free level of fluid in a dipped glass tube will be
Higher than the surface of liquid
The same as the surface of liquid
Lower than the surface of liquid
Unpredictable
The hydraulic mean depth for a circular pipe of diameter (d) is
d/6
d/4
d/2
d
Dimensions of surface tension are
ML°T⁻²
ML°T
ML r²
ML²T²
The ratio of the inertia force to the __________ is called Euler's number.
Pressure force
Elastic force
Surface tension force
Viscous force
A weir is said to be narrow-crested weir, if the width of the crest of the weir is __________ half the height of water above the weir crest.
Equal to
Less than
More than
None of these