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
View Answer
Answer: a
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
View Answer
Answer: a
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
View Answer
Answer: c
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%
View Answer
Answer: a
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
View Answer
Answer: b
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
View Answer
Answer: c
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
View Answer
Answer: d
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
View Answer
Answer: a
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
View Answer
Answer: c
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
View Answer
Answer: c
Explanation: Arithmetic mean diameter DN is given as the ratio of number of particles of size‘d’ to the total number of particles.