Lecture 1 : Units and Dimensions

Question 1

How is specific gravity of a substance calculated?

Answer 1

Density of substance / density of water

• specific gravity is the ratio of density of substance to density of water

Question 2

What is the equation for porosity (relating it with bulk density and solid density)?

Answer 2

1 - bulk density/solid density

Question 3

How to convert moisture content (dry basis) into wet basis?

Answer 3

MC_WB= MC_DB / (1+MC_DB)

Question 4

How to convert moisture content (wet basis) into dry basis?

Answer 4

MC_DB = MC_WB / (1-MC_WB)

Question 5

If pressure of a fluid is above atmospheric pressure, what is the absolute pressure of the fluid?

Answer 5

P_absolute = P_atm + P_gauge

Question 6

If pressure of a fluid is below atmospheric pressure, what is the vacuum pressure of the fluid? (vacuum that is drawn out of the system)

Answer 6

P_vacuum = P_atm - P_abs 

• P_abs is from the vacuum gauge

Question 7

What is the pressure expression involving height of fluid?

Answer 7

P = density x acceleration due to gravity x height

Question 8

What is g, the acceleration due to gravity? State its value and units

Answer 8

9.81 m/s^2

Question 9

For pressures above atmospheric pressure:

The vacuum gauge uses atmospheric pressure as the zero point, and measures the amount of vacuum drawn out of the system. True or False?

Answer 9

False, it uses absolute vacuum as the zero point, and measures the absolute pressure of the fluid.

Question 10

For volumetric flow rate, how to convert 1.8L/s into m^3/S?

Answer 10

1L = 10^-3 m^3

Thus 1.8L/s = 1.8 x 10^-3 m^3/s

Question 11

How to convert millipascal (mpa) to pascal?

Answer 11

multiply by 10^-3