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Which of the following is the correct equation for minimum fluidization velocity for large particles? Here, Dp is the diameter of the particle, ρP and ρF are the density of particle and fluid medium respectively, εmf is the porosity and ΦS is the shape factor.

Correct Answer: Umf2 = \(\frac {Dp (ρP-ρF)g}{1.75ρF}\) × εmf3 × ΦS
Particles are said to be large when the Reynolds number is greater than 1000. The minimum fluidization velocity for large particles is directly proportional to the bed porosity at the point of minimum fluidization and square root of the shape factor of the bed particles.

A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle system (in SI units) is given below:
Δ P/L = 375 × 103 VOM + 10.94 × 106 V2OM (SI units)
If water is to be used as the fluidising medium, in actual operation, the above bed has a height = 1 m. What is the porosity of the fluidised bed?

Which two classes use the Shape class correctly?
A. public class Circle implements Shape { private int radius; }B. public abstract class Circle extends Shape { private int radius; }C. public class Circle extends Shape { private int radius; public void draw(); }D. public abstract class Circle implements Shape { private int radius; public void draw(); }E. public class Circle extends Shape { private int radius; public void draw() { /* code here */ } }F. public abstract class Circle implements Shape { private int radius; public void draw() { /* code here */ } }

A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle system (in SI units) is given below :
Δ P/L = 375 x 103 VOM + 10.94 x 106 V2OM (SI units)
If water is to be used as the fluidising medium, the minimum fluidisation velocity, VOM is

Large, medium and small ships are used to bring water. 4 large ships carry as much water as 7 small ships, 3 medium ships carry the same amount of water as 2 large ships and 1 small ship. 15 large, 7 medium and 14 small ships, each made 36 journeys and brought a certain quantity of water. In how many journeys would 12 large, 14 medium and 21 small ships bring the same quantity ?

Bernoulli's equation for fluid flow is derived following certain assumptions. Out of the assumptions listed below, which set of assumptions is used in derivation of Bernoulli's equation?
1. Fluid flow is frictionless & irrotational
2. Fluid flow is steady
3. Fluid flow is uniform & turbulent
4. Fluid is compressible
5. Fluid is incompressible

3/4th of square were taken to form shape A and the rest was made to form shape B. Shape A was divided into four equal squares (Shape C), what will be the ratio of the one shape C to one shape B.

For turbulent flow (NRe > 2100) of low viscosity fluid (μ > 20cp) in steel pipes, the optimum inside pipe diameter is given by (where, Q = fluid flow rate, ft3/sec.ρ = fluid density, lb/ft3.μ = fluid viscosity, centipoise Di = optimum inside pipe diameter, inches)

Two identical particles have to be distributed among three energy levels. Let rB, rF and rC represent the ratios of probability of finding two particles to that of finding one particle in a given energy state. The subscripts B, F and C correspond to whether the particles are Bosons, Fermions and classical particles, respectively. The rB : rF : rC is equal to

A viscous solution contains particles with a density is to be clarified by centrifugation. The solution density is and its viscosity is 80 cp. The centrifuge has a bowl with and 3 1200 / p ρ = kg m3 ρ = 850 / kg m2r m = 0.02 1 r = 0.01 m and height b=0.25 m. Calculate the critical particle diameter of the largest particles in the exit stream if N=15000 rpm and flow rate q=0.002 m3 /hr?

Which of the following statements are true/false?
1. A minimum rate of wages for the time spent by employees for the production of output is minimum time rate.
2. Minimum piece rate is the rate based on the quantity of the output employees have produced.
3. The guaranteed time rate is a minimum rate of remuneration to apply in the case of employees employed on piece work for the purpose of securing to such employees a minimum rate of wages on a time work basis.
4. A minimum rate of remuneration to apply in the case of employees employed on piece work for the purpose of securing to such employees a minimum rate of wages on a time work basis is overtime rate.