# Mechanical Operations Questions and Answers – Materials of Construction

This set of Mechanical Operations Multiple Choice Questions & Answers (MCQs) focuses on “Materials Of Construction”.

1. _____are commonly used to control product on a horizontal or inclined conveyor.
a) Magnet
b) Cleated
c) Clamped
d) Stock

Explanation: Cleated belt conveyors are commonly used to control product on a horizontal or inclined conveyor, the key attributes for cleated conveyors are the accuracy.

2. What does the below equation represent? a) Froude number
b) Reynold’s number
c) Sherwood number
d) Kick’s number

Explanation: The type of fluidization can be predicted by criteria of Froude number, where Vmf is minimum velocity of flow over the whole cross section area.

3. Fluidization occurs when, Fr is _____
a) 1.5
b) Zero
c) Infinite
d) Unity

Explanation: When the Froude number is less than unity, particulate fluidization occurs and at higher values aggregative fluidization takes place.

4. If the particle are small, the flow is ______
a) Transient
b) Laminar
c) Turbulent
d) Eddy

Explanation: If the particles is very small, the flow through the channels between the particles will be laminar and pressure drop increases.
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5. As the velocity increases, pressure drop ____
a) Increases
b) Decreases
c) Is constant
d) Diverted

Explanation: As the velocity is gradually increased, the pressure drop increase but the particles do not move and the bed height remains same.

6. At the fluidizing point, pressure gradient _____
a) Falls
b) Increases
c) Is zero
d) Is unity

Explanation: At the fluidizing point, the pressure gradient begins to fall because the porosity of the bed increases.

7. Minimum fluidization velocity is calculated by _____
a) Reynold’s equation
b) Dom’s equation
c) Crump equation
d) Ergun’s equation

Explanation: An equation for the minimum fluidization velocity can be obtained by settling the pressure drop across the bed equal to weight of the bed per unit area.

8. What does the below equation represent? a) Reynold’s equation
b) Schmidt equation
c) Ergun’s equation
d) Froude’s equation

Explanation: The above equation is called as the Ergun’s equation, where the dependence of minimum fluidization velocity on Dp.

9. For low Reynold’s number, the terminal velocity ____
a) Falls
b) Increases
c) Is zero
d) Is unity

Explanation: The terminal velocity for individual particles falling in the still air shows that, for low Reynold’s number.

10. The following equation depends upon ______ a) Void fraction
c) Entropy
d) Enthalpy

Explanation: The ratio of the terminal velocity and the fluidization velocity mainly depend mainly on the void fraction at minimum fluidization.

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