Engineering Questions with Answers - Multiple Choice Questions

# Mechanical Operations MCQ’s – Optimum Time Cycle

1 - Question

What does the following equation represents?
Q= K1 ND3
a) Flow of impellor
b) Discharge
c) Velocity
d) Density

Explanation: The quantity of flow is defined as the amount of fluid which moves axially or radially away from the impellor at the surface area of rotation.

2 - Question

What does the following equation represents?
P=QρH
a) Density
b) Discharge
c) Velocity
d) Power

Explanation: The power requirements cannot always be calculated for a system with great degree of reliability, thus the following equation can be used.

3 - Question

What does the below equation represent?

a) Schmidt number of mixing
b) Froude number of mixing
c) Reynold’s number of mixing
d) Dom number of mixing

Explanation: The following represents the Reynold’s number for mixing, where N is the impellor rotational speed and D is the impellor diameter.

4 - Question

What does the following represents?

a) Schmidt number of mixing
b) Froude number of mixing
c) Reynold’s number of mixing
d) Dom number of mixing

Explanation: The following represents the Froude number for mixing, where N is the impellor rotational speed and g is the gravitational constant 32.2 ft/sec2.

5 - Question

What does the below equation represent?

a) Schmidt number
b) Froude number
c) Reynold’s number
d) Power number

Explanation: The power number PO is used in most of the correlations to represent the relationship to system performance.

6 - Question

What does the following represents?

a) Entrainment
b) Flow rate
c) Discharge
d) Throttle

Explanation: From a propeller, the entrainment by the circular jet is given by the above equation, where X is the distance from impellor source not to exceed 100 jet diameters.

7 - Question

The maximum Q/p1/3 for a circular jet is at X= _________
a) 1.71D0
b) 2.5D0
c) 7D0
d) 8.5D0

Explanation: The maximum Q/p1/3 for a circular jet is at X=1.71D0 or in other word the optimum jet origin diameter is 1/17.1 of the distance desired for effective entrainment.

8 - Question

What does the below equation represent?

b) Gravity
c) Centrifugal force
d) Exhaust force

Explanation: The above equation represents the velocity gradient, where P is the power dissipated and other terms are dynamic viscosity and volume.

9 - Question

As the velocity gradient increases, the shear force _______
a) Decreases
b) Increases
c) Remains same
d) Constant

Explanation: We know that the rate of particulate collision the rate is directly proportional to the velocity gradient, G must be sufficient to furnish desired rate.

10 - Question

Calculate G, if two mercury particles are moving at 2 m/sec to each other at a distance of 10 m?
a) 0.2
b) 5
c) 0.5
d) 2