Defintion + Exam Qs

Question 1

What is absolute pressure?

Answer 1

It is the actual pressure at a given position, measured relative to absolute vacuum.

Question 2

What can we say about pressure in a continuously distributed uniform static fluid?

Answer 2

-it varies only with vertical distance
-independent of the shape of the container
-pressure the same at all points on horizontal plane

Question 3

What does pascal principle state?

Answer 3

Pressure is transmitted, undiminished in a closed static fluid
Pressure at any point = applied pressure and hydrostatic pressure change

Question 4

What is a manometer?

Answer 4

-static column with one or more multiple fluids that can be used to measure pressure difference between 2 points

Question 5

What is the pressure gradient ?

Answer 5

-it is a surface force that acts on the sides of an element

Question 6

What is Specific gravity?

Answer 6

-dimensionless ratio of the densities of 2 materials .
-reference material if often a liquid (water)

Question 7

What is specific weight?

Answer 7

-weight per unit volume
-density x g

Question 8

How do viscosities of a liquid change with temperature?

Answer 8

-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.

Question 9

How does viscosity of a gas change with temperature?

Answer 9

-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.

Question 10

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?

Answer 10

Solid

Question 11

What is a piezometer?

Answer 11

• a device used to measure liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity

Question 12

What is a barometer?

Answer 12

-a scientific instrument that is used to measure air pressure in a certain environment

Question 13

Where does the average force and average pressure act On wall?

Answer 13

At its centroid

Question 14

When does the resultant force of a force ‘F’ at distance ‘y’ from the surface act ?

Answer 14

Centre of pressure . (2h/3)

Question 15

What principle is used to find centre of pressure.

Answer 15

-principle of balancing moments

Question 16

A simple U-tube manometer can measure negative gauge pressures?

Answer 16

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.

Question 17

If the tank is moving vertically upwards, which part of it’s structure is subjected to maximum load?

Answer 17

base

Question 18

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

Answer 18

false. The water in tank is at rest even if the tank is moving. A fluid at rest experiences no shear stress.

Question 19

What is rigid body motion?

Answer 19

• 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

Question 20

What are the things we need to consider for uniform rigid body motion?

Answer 20

• 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

Question 21

what are the things we need to consider for rotational rigid body motion?

Answer 21

Special case of constant rotation around � - axis
* Acceleration is towards the centre of rotation
* Gravitational acceleration remains

Question 22

For compressible fluid flow in a pipe, if both fluid specific gravity and pipe diameter decreases, what is the resulting effect on the velocity?

Answer 22

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.

Question 23

The continuity equation is based on the principle of?

Answer 23

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.

Question 24

what is a boundary

Answer 24

-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