Mechanical Properties Of Fluids

Question 2

What is the formula for density?

Answer 2

Density = \frac{mass}{volume} (kg m^{-3})

Question 3

What is the formula for specific weight?

Answer 3

Specific weight = \frac{weight}{volume} = \rho g (kg m^{-2} s^{-2})

Question 4

How is relative density defined?

Answer 4

Relative density = \frac{density of given liquid}{density of pure water at 4^{\circ} C} (Unitless)

Question 5

What is the formula for pressure?

Answer 5

Pressure = \frac{normal force}{Area} = \frac{thrust}{Area} (Nm^{-2})

Question 6

What is the pressure difference between two points at depth h?

Answer 6

(P_2 - P_1) = h\rho g

Question 7

What is the pressure in a fluid when an elevator accelerates upwards?

Answer 7

P = h\rho(g + a_0)

Question 8

What defines steady flow?

Answer 8

Steady flow is when fluid characteristics like velocity, pressure, and density at a point do not change with time.

Question 9

What is a streamline in fluid flow?

Answer 9

In steady flow, all particles passing through a given point follow the same path, called a streamline.

Question 10

What is laminar flow?

Answer 10

Laminar flow is when fluid particles move along well-defined streamlines that are straight and parallel.

Question 11

What is the difference between compressible and incompressible flow?

Answer 11

In compressible flow, density varies from point to point; in incompressible flow, density remains constant.

Question 12

What is the equation of continuity?

Answer 12

A_1v_1 = A_2v_2; Av = constant.

Question 13

What is Bernoulli’s theorem?

Answer 13

P + \frac{1}{2}\rho v^2 + \rho gh = constant

Question 14

What is the kinetic energy per unit volume?

Answer 14

\frac{Kinetic Energy}{volume} = \frac{1}{2} \rho v^2

Question 15

What is the potential energy per unit volume?

Answer 15

\frac{Potential Energy}{volume} = \rho gh

Question 16

What is the pressure energy per unit volume?

Answer 16

Pressure energy per unit volume = P

Question 17

What is the rate of flow?

Answer 17

Volume of water flowing per second Q = A_1v_1 = A_2v_2

Question 18

What is the velocity of efflux?

Answer 18

Velocity of efflux v = \sqrt{2gh}

Question 19

What is the horizontal range formula?

Answer 19

Horizontal range R = 2\sqrt{h(H-h)}

Question 20

What is Newton’s law of viscosity?

Answer 20

F = \eta A \frac{dv}{dy}

Question 21

What are the SI units of viscosity?

Answer 21

SI Units of \eta: \frac{Ns}{m^2}

Question 22

What is Poiseuille’s formula?

Answer 22

Poiseuille’s formula (v) = \frac{\pi pr^4}{8 \eta l}

Question 23

What is the terminal velocity formula?

Answer 23

Terminal velocity v_T = \frac{2}{9} \frac{r^2 (\rho - \sigma) g}{\eta}

Question 24

What is Reynolds number?

Answer 24

Reynold’s number R_e = \frac{\rho v D}{\eta}

Question 25

What does R_e < 1000 indicate?

Answer 25

R_e < 1000 indicates laminar flow.

Question 26

What does R_e > 2000 indicate?

Answer 26

R_e > 2000 indicates turbulent flow.

Question 27

What is surface tension?

Answer 27

Surface tension is a property of liquid that behaves like a stretched elastic membrane.

Question 28

What is cohesive force?

Answer 28

Cohesive force is the force acting between molecules of the same substance.

Question 29

What is adhesive force?

Answer 29

Adhesive force is the force acting between different types of molecules.

Question 30

How does temperature affect surface tension?

Answer 30

Surface tension decreases with increasing temperature.

Question 31

What is the definition of surface tension?

Answer 31

Surface tension is the force acting per unit length of an imaginary line drawn on the liquid surface.

Question 32

What is the angle of contact?

Answer 32

The angle enclosed between the tangent plane at the liquid surface and the tangent plane at the solid surface.

Question 33

What does an angle of contact θ < 90° indicate?

Answer 33

θ < 90° indicates a concave shape; liquid rises in capillary.

Question 34

What does an angle of contact θ > 90° indicate?

Answer 34

θ > 90° indicates a convex shape; liquid falls in capillary.

Question 35

What is the formula for capillary rise?

Answer 35

Capillary rise h = \frac{2T \cos\theta}{r \rho g}

Question 36

What is the formula for density?

Answer 36

Density = \frac{mass}{volume} (kg m^{-3})

Question 37

What is the formula for specific weight?

Answer 37

Specific weight = \frac{weight}{volume} = \rho g (kg m^{-2} s^{-2})

Question 38

How is relative density defined?

Answer 38

Relative density = \frac{density of given liquid}{density of pure water at 4^{\circ} C} (Unitless)

Question 39

What is the formula for pressure?

Answer 39

Pressure = \frac{normal force}{Area} = \frac{thrust}{Area} (Nm^{-2})

Question 40

What is the pressure difference between two points at depth h?

Answer 40

(P_2 - P_1) = h\rho g

Question 41

What is the pressure in a fluid when an elevator accelerates upwards?

Answer 41

P = h\rho(g + a_0)

Question 42

What defines steady flow?

Answer 42

Steady flow is when fluid characteristics like velocity, pressure, and density at a point do not change with time.

Question 43

What is a streamline in fluid flow?

Answer 43

In steady flow, all particles passing through a given point follow the same path, called a streamline.

Question 44

What is laminar flow?

Answer 44

Laminar flow is when fluid particles move along well-defined streamlines that are straight and parallel.

Question 45

What is the difference between compressible and incompressible flow?

Answer 45

In compressible flow, density varies from point to point; in incompressible flow, density remains constant.

Question 46

What is the equation of continuity?

Answer 46

A_1v_1 = A_2v_2; Av = constant.

Question 47

What is Bernoulli's theorem?

Answer 47

P + \frac{1}{2}\rho v^2 + \rho gh = constant

Question 48

What is the kinetic energy per unit volume?

Answer 48

\frac{Kinetic Energy}{volume} = \frac{1}{2} \rho v^2

Question 49

What is the potential energy per unit volume?

Answer 49

\frac{Potential Energy}{volume} = \rho gh

Question 50

What is the pressure energy per unit volume?

Answer 50

Pressure energy per unit volume = P

Question 51

What is the rate of flow?

Answer 51

Volume of water flowing per second Q = A_1v_1 = A_2v_2

Question 52

What is the velocity of efflux?

Answer 52

Velocity of efflux v = \sqrt{2gh}

Question 53

What is the horizontal range formula?

Answer 53

Horizontal range R = 2\sqrt{h(H-h)}

Question 54

What is Newton's law of viscosity?

Answer 54

F = \eta A \frac{dv}{dy}

Question 55

What are the SI units of viscosity?

Answer 55

SI Units of \eta: \frac{Ns}{m^2}

Question 56

What is Poiseuille's formula?

Answer 56

Poiseuille's formula (v) = \frac{\pi pr^4}{8 \eta l}

Question 57

What is the terminal velocity formula?

Answer 57

Terminal velocity v_T = \frac{2}{9} \frac{r^2 (\rho - \sigma) g}{\eta}

Question 58

What is Reynolds number?

Answer 58

Reynold's number R_e = \frac{\rho v D}{\eta}

Question 59

What does R_e < 1000 indicate?

Answer 59

R_e < 1000 indicates laminar flow.

Question 60

What does R_e > 2000 indicate?

Answer 60

R_e > 2000 indicates turbulent flow.

Question 61

What is surface tension?

Answer 61

Surface tension is a property of liquid that behaves like a stretched elastic membrane.

Question 62

What is cohesive force?

Answer 62

Cohesive force is the force acting between molecules of the same substance.

Question 63

What is adhesive force?

Answer 63

Adhesive force is the force acting between different types of molecules.

Question 64

How does temperature affect surface tension?

Answer 64

Surface tension decreases with increasing temperature.

Question 65

What is the definition of surface tension?

Answer 65

Surface tension is the force acting per unit length of an imaginary line drawn on the liquid surface.

Question 66

What is the angle of contact?

Answer 66

The angle enclosed between the tangent plane at the liquid surface and the tangent plane at the solid surface.

Question 67

What does an angle of contact θ < 90° indicate?

Answer 67

θ < 90° indicates a concave shape; liquid rises in capillary.

Question 68

What does an angle of contact θ > 90° indicate?

Answer 68

θ > 90° indicates a convex shape; liquid falls in capillary.

Question 69

What is the formula for capillary rise?

Answer 69

Capillary rise h = \frac{2T \cos\theta}{r \rho g}