Hydraulics Objective Questions Flashcards
Fluid is a substance that
cannot remain at rest under action of any shear force
Density of water is maximum at
4 degrees Celsius
Property of a fluid by which its own molecules are attracted is called
cohesion
Property of a fluid by which molecules of different kinds are attracted to each other is called
adhesion
The normal stress in a fluid will be constant in all direction at a point only if
it is at rest
Specific weight of sea water is more that of pure water because it contains
dissolved air, dissolved salt, and suspended matter
Free surface of a liquid tends to contract to the smallest possible area due to force of
surface tension
A liquid would wet the solid, if adhesion forces, as compared to cohesion forces are
more
Barometer is used to measure
atmospheric pressure
Manometer is used to measure
pressure in pipes, channels etc
If cohesion between molecules of a liquid is greater than adhesion between fluid and glass, then the free level of fluid in a dipped glass tube will be
lower than the surface of a liquid
When a fluid is subjected to resistance, it undergoes a volumetric change due to
compressibility
Liquids transmit pressure equally in all the directions. This is according to
Pascal’s Law
The rise or depression of a liquid in a tube due to surface tension with an increase in size of tube will
decrease
Mercury is often used in barometer because
(1) the height of barometer will be less (2) its vapor pressure is so low that it may be neglected
The point in the immersed body through which the resultant pressure of the liquid may be taken to act is known as
center of pressure
Which of the following is the correct relation between centroid (cg) and the center of pressure (cp) of a plane submerged in a liquid?
cp is either at cg or below it
The total pressure force on a plane area is equal to the area multiplied by the intensity of pressure at the centroid, if
(1) the area is horizontal, (2) the area is vertical, (3) the area is inclined
Choose the wrong statement (1) The horizontal component of the hydrostatic force on any surface is equal to the normal force on the vertical projection of the surface, (2) The horizontal component acts through the center of pressure for the vertical projection, (3) The vertical component of the hydrostatic force on any surface is equal to the weight of the volume of the liquid above the area, (4) The vertical component passes through the center of pressure of the volume
Statement 4 is the wrong statement (Explanation: The statement is wrong because the “center of pressure” is typically associated with the resultant of a pressure distribution acting on a surface (like a submerged surface in a fluid), not a volume.)
Center of pressure on an inclined plane is
below the centroid
Can the center of pressure for a vertical plane submerged surface ever be above the center of gravity?
No
In a vertically submerged plane surface, pressure at every point remains the same.
False
For an inclined plate, the pressure intensity at every point differs
True
The magnitude of total pressure and center of pressure is independent on the shape of the submerged plane surface.
False
What is the variation of total pressure with depth for any submerged surface if we neglect variation in the density?
Linear
The resultant upward pressure of a fluid on a floating body is equal to the weight of the fluid displaced by the body. This definition is according to
Archimedes’ Principle
The resultant upward pressure of the fluid on an immersed body is called
buoyant force
What is the principal cause of action of buoyant force on a body submerged partially or fully in fluid?
Displacement of fluid due to submerged body
The center of gravity of the volume of the liquid displaced by an immersed body is called
center of buoyancy