This set of Food Processing Unit Operations Multiple Choice Questions & Answers (MCQs) focuses on “ Dimensions and Units”.

1. The SI unit of film heat transfer coefficient is __________

a) W K/m^{2}

b) Wm^{2}K

c) (m^{2}K)/W

d) W/ (m^{2}K)

View Answer

Explanation: The SI unit of film heat transfer coefficient isW K/m

^{2}. The heat transfer through convection between a solid and a fluid is measured using heat transfer coefficient. It depends on 1) Hydrodynamic characteristics of its flow, 2)Hydrodynamic characteristics of its flow and 3) Hydrodynamic and thermal boundary conditions.

2. Unit of specific gravity is _________

a) g/cm

b) g/cm^{3}

c) kg/m^{3}

d) dimensionless

View Answer

Explanation: The Specific Gravity of liquids and solids is defined as dimensionless unit. It is the ratio of density of a material to the density of water at a given temperature.

3. The SI unit of dynamic viscosity is _____________

a) pascal-second

b) pascal- minute

c) poise-second

d) poise

View Answer

Explanation: The SI unit of dynamic viscosity is the pascal-second or kilogram per meter per second. The CGS unit of dynamic viscosity is known as poise (P) which is named after Jean Leonard Marie Poiseuille.

4. Are these statements about the dimensionless quantities true?

Statement 1: A quantity which does not have any physical units.

Statement 2: Relative density and Reynolds number are examples of the dimensionless quantities.

a) True, False

b) True, True

c) False, True

d) False, False

View Answer

Explanation: A quantity which does not have any physical units is called as dimensionless quantities. The relative density is the dimensionless quantity which is defined as the ratio of the density of a component to density of the given reference component. The Reynold number (R) is also a dimensionless quantity that is used to determine whether the fluid is following laminar flow (R<2300) or turbulent flow(R>4000).

5. What is the dimension of surface tension?

a) MLT^{-2}

b) LT^{-2}

c) MT^{-2}

d) Dimensionless

View Answer

Explanation: The surface tension is defined as the force per unit length. The dimensional formula of force is MLT

^{-2}and for length, it is L. Therefore, the dimension of surface tension is MT

^{-2}.

6. Which of the following statements about SI units are correct?

Statement 1: There are 8 base units in SI system.

Statement 2: Gram and centimeter comes under the SI units.

a) True, False

b) True, True

c) False, True

d) False, False

View Answer

Explanation: There are 7 base units in SI system. They are: kilogram (kg) for mass, kelvin (K) for temperature, mole (mol) for the amount of a substance, ampere (A) for electric current, candela (cd) for luminous intensity, second (s) for time and meter (m) for distance.

7. What is the full form of SI unit?

a) International System of units

b) Indian Standards of unit

c) Standard International unit

d) International standard of units

View Answer

Explanation: The International System of Units is the contemporary form of the metric systems and is the most commonly used system of the measurement.

8. What is the Full form of CGS unit?

a) Centimeter–gram–second

b) Centralized grand system

c) Centimeter gram system

d) Centimeter grand system

View Answer

Explanation: Centimeter–gram–second system of units is a type of the metric system which is based on centimeter as unit of length, gram as unit of mass and second as unit of time. This is not commonly used metric type nowadays. SI units are used widely than CGS units.

9. What are the base quantities ofDimensional formula?

a) Massand length only

b) Mass and second only

c) Length and second only

d) Mass, length and second

View Answer

Explanation: The base quantities of Dimensional formula are mass [M], length [L], Second [S]. The dimensional formula is based on the relationships between physical quantities involved, which is expressed in terms of three fundamental quantities known as mass, length and second.

10. Is Nusselt numberconsidered as a dimensionless quantity?

a) True

b) False

View Answer

Explanation: Nusselt number is considered as dimensionless quantity which is used in calculation of the heat transfer between a moving fluid and a solid body. It is defined as the ratio of convective to conductive heat transfer across a boundary.

**Sanfoundry Global Education & Learning Series – Food Processing Unit Operations.**

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