Engineering Questions with Answers - Multiple Choice Questions

# Mechanical Operations MCQ’s – Average Particle Size

1 - Question

The volume surface mean diameter, can be defined as ___
a) 6/ΦsAwPp
b) 6/ΦsAwVp
c) 6/ΦsAwDp
d) 6/ΦsAwSp

Explanation: The average particle size of a mixture is defined by the volume surface mean diameter Ds which is related to Aw as 6/ΦsAwPp.

2 - Question

Volume of any particle, can be given as ______
a) a*Dp3
b) a*Dp2
c) a*Dp
d) a*Sp

Explanation: The volume of any particle is proportional to the cube of the diameter of the given shape
i.e. Vp = a*Dp3, where a is shape factor.

3 - Question

Crushing efficiency is the ratio of ____
a) Energy wasted to Energy wasted
b) Energy wasted to Energy created
c) Energy created Energy wasted
d) Energy Destroyed to Energy wasted

Explanation: The ratio of surface energy created by crushing to the energy absorbed y the solid is defined as the crushing efficiency nc

4 - Question

Crushing Efficiency ranges between ____
a) 0.06 and 1%
b) 0.05 and 2%
c) 0.5 to 5%
d) 60 to 90%

Explanation: The surface energy create is comparatively low with the total mechanical energy stored in the material, crushing efficiency is therefore low.

5 - Question

The ratio of energy absorbed to the energy input is defined as the ___
a) Crushing Efficiency
b) Mechanical Efficiency
c) Work Done
d) Final Power

Explanation: The mechanical efficiency id denoted by nm and is defined as the ratio of energy absorbed to the energy input (w).

6 - Question

On which of the equation below, Energy absorbed can be calculated?
a) es(A1-A2)/Dp
b) es(A1-A2)/nc
c) es(A1-A2)/wc
d) es(A1-A2)/sc

Explanation: The energy absorbed can be given as es(A1-A2)/wc, where es is the surface energy per unit area and A1 and A2 are the area of mass of feed and product.

7 - Question

The power required, can be given by ____
a) w*Dp
b) w*As
c) w*nc
d) w*m

Explanation: The power required by the machine can be calculate by P = w*m, where m is the feed rate and the w is the energy absorbed.

8 - Question

The surface are of the particle, is given as _____
a) πd2s
b) Φd2s
c) πV2s
d) πP2s

Explanation: If Sp is taken as to be the surface area of the particle, then it is given by πd2s, where ds is the diameter of the sphere particle.

9 - Question

The Bubble or Drop size diameter, is referred to _____
a) Frisch diameter
b) Bubble diameter
c) Sauter diameter
d) Sphere diameter

Explanation: When surface area and the bubble are controlling parameters then, in such cases these diameters are called as Sauter diameter.

10 - Question

What is arithmetic mean diameter?
a) Sidi/Si
b) Vidi/Vi
c) Nidi/Ni
d) Widi/Wi