Defintion + Exam Qs Flashcards
What is absolute pressure?
It is the actual pressure at a given position, measured relative to absolute vacuum.
What can we say about pressure in a continuously distributed uniform static fluid?
-it varies only with vertical distance
-independent of the shape of the container
-pressure the same at all points on horizontal plane
What does pascal principle state?
Pressure is transmitted, undiminished in a closed static fluid
Pressure at any point = applied pressure and hydrostatic pressure change
What is a manometer?
-static column with one or more multiple fluids that can be used to measure pressure difference between 2 points
What is the pressure gradient ?
-it is a surface force that acts on the sides of an element
What is Specific gravity?
-dimensionless ratio of the densities of 2 materials .
-reference material if often a liquid (water)
What is specific weight?
-weight per unit volume
-density x g
How do viscosities of a liquid change with temperature?
-viscosity of a liquid is due to cohesion between its molecules. With the increase in temperature of a liquid , cohesion decreases leading to a fall in viscosity.
How does viscosity of a gas change with temperature?
-viscosity of a gas is due to the momentum transfer between its molecules, with the increase in the temperature of a gas , molecular motion increase Leading to a rise in viscosity.
A small shear force is applied on an element and then removed. If the element regains its original position , what kind of element can it be?
Solid
What is a piezometer?
- a device used to measure liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity
What is a barometer?
-a scientific instrument that is used to measure air pressure in a certain environment
Where does the average force and average pressure act On wall?
At its centroid
When does the resultant force of a force ‘F’ at distance ‘y’ from the surface act ?
Centre of pressure . (2h/3)
What principle is used to find centre of pressure.
-principle of balancing moments
A simple U-tube manometer can measure negative gauge pressures?
true. he height of the manometric fluid in a U-tube manometer in the test column would fall if there is a positive gauge pressure. The height would increase if there is a negative gauge pressure.
If the tank is moving vertically upwards, which part of it’s structure is subjected to maximum load?
base
A tank of water is moving with a constant velocity for a long period of time. A non-zero shear stress will be imposed on the fluid by the tank walls, due to the dynamic motion of the tank
false. The water in tank is at rest even if the tank is moving. A fluid at rest experiences no shear stress.
What is rigid body motion?
- Rigid body motion is a special case, where the fluid has reached an equilibrium, e.g. under constant acceleration.
-So there are no stresses or strains in the fluid
What are the things we need to consider for uniform rigid body motion?
- There is a net acceleration in a non-vertical direction
- We still consider the fluid to be a hydrostatic fluid
- But it has an adjusted free-surface & depth direction.
- Constant pressure lines are no longer horizontal
- ‘depth’ is no longer vertical
what are the things we need to consider for rotational rigid body motion?
Special case of constant rotation around � - axis
* Acceleration is towards the centre of rotation
* Gravitational acceleration remains
For compressible fluid flow in a pipe, if both fluid specific gravity and pipe diameter decreases, what is the resulting effect on the velocity?
According to continuity equation, for compressible fluid, rho A v is constant, where rho represents fluid density, A represents flow area, and v represents flow speed. Hence, as density and area decreases, velocity is bound to increase.
The continuity equation is based on the principle of?
According to the Continuity Equation, if no fluid is added or removed from the pipe in any length then the mass passing across different sections shall be the same.
This is in accordance with the principle of conservation of mass which states that matter can neither be created nor be destroyed.
what is a boundary
-the real or imaginary surface that separates the system from its surroundings.
-The boundaries of a system can be fixed or movable. The boundary has zero thickness, no mass, and no volume
