Mechanical Operations - Study Mode

Show All Answers

[#151] According to Bond crushing law, the work required to form particle of size 'D' from very large feed is (where $${left( {frac{{ ext{S}}}{{ ext{V}}}}
ight)_{ ext{p}}}$$ and $${left( {frac{{ ext{S}}}{{ ext{V}}}}
ight)_{ ext{f}}}$$ are surface to volume ratio of the product and feed respectively).

(A) $${left( {frac{{ ext{S}}}{{ ext{V}}}} ight)_{ ext{p}}}$$

(B) $$sqrt {{{left( {frac{{ ext{S}}}{{ ext{V}}}} ight)}_{ ext{p}}}} $$

(C) $$left( {frac{{ ext{S}}}{{ ext{V}}}} ight)_{ ext{p}}^2$$

(D) $${left( {frac{{ ext{S}}}{{ ext{V}}}} ight)_{ ext{f}}}$$

Correct Answer

(B) $$sqrt {{{left( {frac{{ ext{S}}}{{ ext{V}}}} ight)}_{ ext{p}}}} $$

[#152] Angle of nip of the crushing rolls does not depend upon the

(A) Diameter of the rolls

(B) Speed of the rolls

(C) Product size

(D) Feed size

Correct Answer

(B) Speed of the rolls

[#153] The distribution given by microscopic analysis of powder is

(A) Number

(B) Length

(C) Area

(D) Volume

Correct Answer

(A) Number

[#154] For Indian standard (IS) screens, the mesh number is equal to its aperture size expressed to the nearest deca-micron (0.01 mm). Aperture width of IS screen of mesh number 50 will be approximately __________ microns.

(A) 5

(B) 50

(C) 500

(D) 5000

Correct Answer

(C) 500

[#155] Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripherial velocity, m/sec. W = width of rolls, m. Dr = distance between rolls, ρ = density of material to be crushed, kg/m 3 . here V = πN.D, where N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m)

(A) 3.6 V.W.Dr.ρ

(B) 3.6 V.W.ρ

(C) 3.6 W.Dr.ρ

(D) 3.6 V.W.Dr/ρ

Correct Answer

(A) 3.6 V.W.Dr.ρ