## Machine Design MCQ Set 1

1. What results due to addition of surfactants?

a) Ease of diffusion

b) Interfacial mass transfer resistance

c) Ease of mass transfer

d) A cloud over the liquid interface

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2. Which of the following is true about rate of mass transfer in gas?

a) N_{A} = k_{p}(p_{ab}-p_{ai})

b) N_{A} = k_{p}(c_{ab}-c_{ai})

c) N_{A} = k_{c}(p_{ab}-p_{ai})

d) N_{A} = k_{c}(c_{ab}-c_{ai})

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3. Which of the following is true about rate of mass transfer in liquid?

a) N_{A} = k_{p}(p_{ab}-p_{ai})

b) N_{A} = k_{p}(c_{ab}-c_{ai})

c) N_{A} = k_{c}(p_{ab}-p_{ai})

d) N_{A} = k_{c}(c_{ab}-c_{ai})

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4. Which of the following is the incorrect form of Henry’s law?

a) p_{A}=H_{A}x_{A}

b) p_{A} = c_{A}/H_{A}

c) X_{a}=H_{A}x_{A}

d) Y_{A} = H_{A}x_{A}

### View Answer

_{a}=H

_{A}x

_{A}.

5. Which of the following is true about overall mass transfer coefficient KL?

a) K_{L} =H_{A}/kp +1/kc

b) 1/K_{L} = H_{A}/kp +1/kc

c) K_{L} =1/H_{A} kp +1/kc

d) 1/K_{L} = H_{A}/kp +kc

### View Answer

_{L}= H

_{A}/kp +1/kc.

6. What is the correct expression for overall mass transfer coesfficient based on mole fraction driving forces?

a) 1/K_{x} = 1/K_{A}k_{y} + 1/k_{x}

b) K_{x} = 1/K_{A}k_{y} + 1/k_{x}

c) 1/K_{x} = K_{A}/k_{y} + 1/k_{x}

d) 1/K_{x} = 1/K_{A}k_{x} + 1/k_{y}

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_{x}= 1/K

_{A}k

_{y}+ 1/k

_{x}is the correct representation of overall mass transfer coefficient.

7. What will be the overall mass transfer coefficient when the resistance by gas phase is negligible?

a) 1/K_{x} = 1/K_{A}k_{y} + 1/k_{x}

b) K_{x} = 1/K_{A}k_{y} + 1/k_{x}

c) 1/K_{x} = K_{A}/k_{y} + 1/k_{x}

d) 1/K_{x} = 1/K_{A}k_{x} + 1/k_{y}

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8. What are the correct SI units for kx, ky?

a) kmol/s-m

b) kmol/s-m_{2}

c) mol/s-m_{2}

d) kmol/s

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_{2}.

9. Which of the following is true for mass transfer across liquid-liquid interface?

a) 1/K_{x}^{(2)} = 1/K_{A}k_{x}^{(1)} + 1/k_{y}^{(2)}

b) 1/K_{x}^{(2)} = 1/K_{A}k_{y}^{(2)} + 1/k_{x}^{(2)}

c) 1/K_{x}^{(2)} = 1/K_{A}k_{x}^{(1)} + 1/k_{x}^{(2)}

d) 1/K_{x}^{(2)} = 1/k_{y}^{(1)} + 1/k_{x}^{(2)}

### View Answer

_{x}

^{(2)}= 1/K

_{A}k

_{x}

^{(1)}+ 1/k

_{x}

^{(2)}holds true.

10. What is the SI unit of kp?

a) kmol/s-m_{2}-pa

b) kmol/s-m-kpa

c) kmol/m_{2}-kpa

d) kmol/s-m_{2}-kpa

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_{2}-kpa.

## Machine Design MCQ Set 2

1. The molar diffusion flux for a cylinder with inner radius r_{1} and outer radius r_{2} is directly proportional to:

a) Ln(r_{2}/r_{1})

b) R_{2}/r_{1}

c) 1/ln(r_{1}/r_{2})

d) 1/ln(r_{2}/r_{1})

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_{1}and outer radius r

_{2}is 2LD

_{ab}(c

_{a1}-c

_{a2})/ ln(r

_{2}/r

_{1}).

2. The molar diffusion flux for a plane wall with thickness z_{2}-z_{1} is directly proportional to:

a) Z_{2}

b) Z_{2}-z_{1}

c) 1/z_{2}-z_{1}

d) Z_{1}-z_{2}

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_{2}-z

_{1}is D

_{ab}(c

_{a1}-c

_{a2})/ z

_{2}-z

_{1}.

3. The molar diffusion flux for a spherical shell with inner radius r_{1} and outer radius r_{2} is directly proportional to

a) 4r1r_{2}/r_{2}-r_{1}

b) r_{2}-r1/4r1r_{2}

c) r1r_{2}/r_{2}-r_{1}

d) 2r1r_{2}/r_{2}-r_{1}

### View Answer

_{1}and outer radius r

_{2}is 4r

_{1}r

_{2}D

_{ab}(c

_{a1}-c

_{a2})/r

_{2}-r

_{1}.

4. For which mass transfer the area log mean is considered?

a) Through a sphere

b) Through a cylinder

c) Through a wall

d) Through a ball

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_{ab}(c

_{a1}-c

_{a2})/ ln(r

_{2}/r

_{1}).Hence log mean of the area is considered.

5. For which mass transfer the area geometric mean is considered?

a) Through a sphere

b) Through a cylinder

c) Through a wall

d) Through a pipe

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_{1}and outer radius r

_{2}is 4r

_{1}r

_{2}D

_{ab}(c

_{a1}-c

_{a2})/r

_{2}-r

_{1}.Hence the geometric mean area is considered.

6. The molar diffusion rate of A in stationary B in only z direction is given by:

a) D_{ab}A(ΔC_{a}/Δz)

b) D_{ab}A(Δz)

c) -D_{ab}A(ΔC_{a}/Δz)

d) D_{ab}A(ΔC_{a})

### View Answer

_{ab}A(ΔC

_{a}/Δz).

7. For one dimensional diffusion in the radial direction only for cylinder and sphere, the fick’s second law becomes:

a) ΔC_{a}/ΔT= D_{ab}/r(Δ/Δr(rΔCa/Δr)

b) ΔC_{a}/ΔT= D_{ab}/(Δ/Δr(ΔCa/Δr)

c) -ΔC_{a}/ΔT= D_{ab}/r(Δ/Δr(rΔCa/Δr)

d) ΔC_{a}/ΔT= D_{ab}/r(Δ/Δr(r/Δr)

### View Answer

_{a}/ΔT= D

_{ab}/r(Δ/Δr(rΔCa/Δr).

8. The fick’s second law is analogous to:

a) Newton;s second law

b) Newton’s third law

c) Fourier’s second law

d) Fourier’s first law

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_{a}is replaced by temperature T and and D

_{ab}by thermal diffusivity.

9. Which equation is concerned with adsorption equilibria.

a) Gibb’s equation

b) Fourier’s law

c) Fick’s law

d) Freundlich’s equation

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^{1/n}is concerned with adsorption equilibria.

10. For a wetted watch tower, what is the area of mass transfer?

a) Rectangular

b) Spherical

c) Cylindrical

d) Hexagonal

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## Machine Design MCQ Set 3

1. The equation of motion for the liquid film in fully developed laminar flow in y-direction is:

a) µd^{2}u_{y}/dx^{2} + ρg =0

b) µd^{2}u_{y}/dy^{2} + ρg =0

c) µd^{2}u_{y}/dz^{2} + ρg =0

d) µd^{2}u_{y}/dx^{2} = 0

### View Answer

^{2}u

_{y}/dz

^{2}+ ρg =0.

2. Which two forces is the reynold’s number a ratio of?

a) Gravitational force and interfacial force

b) Interfacial force and viscous force

c) Thermal conductivity and electrical conductivity

d) Conduction and convection

### View Answer

_{re}= 4τ/µ is the ratio of interfacial and viscous force.

3. What value of Reynold’s number is obtained with water?

a) 8

b) 16

c) 25

d) 50

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4. What value of reynold’s number represents a laminar flow?

a) 3

b) 2500

c) 5000

d) 78

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5. Which of the following is correct about Reynold’s number?

a) 3less thanN_{re}less than1200

b) 3less than

c) 25less than

d) 8less than

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6. Prandtl’s number is the ratio of which two quantities?

a) Momentum conductivity and thermal conductivity

b) Coefficient of convection to thermal conductivity

c) Momentum diffusivity and thermal diffusivity

d) Interfacial force and viscous force

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7. Which of the following is true about prandtl’s number?

a) N_{pr} = C_{p}µ/k

b) N_{pr} = C_{p}k/µ

c) N_{pr} = C_{v}µ/k

d) N_{pr} = C_{p}µ

### View Answer

_{pr}= C

_{p}µ/k.

8. What is the physical significance of nusselt’s number?

a) Ratio of convective heat transfer to conductive heat transfer

b) Ratio of convective heat transfer to conductive heat transfer

c) Ratio of total heat transfer to conductive heat transfer

d) Ratio of total transfer to convective heat transfer

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9. What is the correct formula for nusselt’s number?

a) hµ/k

b) hρ/k

c) hL/k

d) hΔTL/k

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10. Which of the following is most true?

a) N_{a} = kcA(c_{ai} – c_{a})

b) N_{a} = kcAΔc

c) N_{a} = kcA(c_{ai} – c_{a})_{mean}

d) N_{a} = kcA(c_{ai} – c_{a})_{log mean}

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## Machine Design MCQ Set 4

1. Which of the following is true about turbulent flow?

a) N_{re} greater than 2000

b) N_{re} greater than 4000

c) N_{re} greater than 5000

d) N_{re} greater than 6000

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2. Which of the following reynold’s number represents a turbulent flow?

a) 500

b) 700

c) 2500

d) 6000

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3. Which of the following is present in turbulent flow mass transfer?

a) Slow mass transfer

b) Less mass transfer

c) Eddy currents

d) Eddy diffusion

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4. What is the physical significance of drag coefficient?

a) It is drag force divided by projected area and velocity head

b) It is the ratio of pipe wall shear stress and velocity head

c) It is the ratio of inertial forces to viscous force

d) It is the ratio of inertial force to surface tension force

### View Answer

_{d}=2F

_{D}/Au

^{2}ρ is drag force divided by projected area and velocity head.

5. What is the physical significance of weber number?

a) It is drag force divided by projected area and velocity head

b) It is the ratio of pipe wall shear stress and velocity head

c) It is the ratio of inertial forces to viscous force

d) It is the ratio of inertial force to surface tension force

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6. What is the physical significance of lewis number?

a) It is the ratio of bulk transfer mass and molecular diffusion

b) It is the ratio of thermal diffusivity to mass diffusivity

c) It is the ratio of conductive mass transfer to molecular diffusion

d) It is the ratio of mass transfer to mass capacity

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7. What is the Sherwood number analogous to?

a) Schmidt number

b) Lewis number

c) Nusselt number

d) Prandtl number

### View Answer

_{sh}=K

_{c}L/D

_{ab}is analogous to nusselt number.

8. Which of the following equations is referred as reynold’s analogy?

a) f/c = k_{c}/u_{x}

b) f/c = k_{c}u_{x}

c) f/2 = k_{c}u_{x}

d) f/2 = k_{c}/u_{x}

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_{c}/u

_{x}is referred to as reynold’s analogy.

9. For what condition does the equation for reynold’s analogy equals to equation by Chilton-colburn analogy.

a) N_{pr}=N_{re}=1

b) N_{pr}=N_{se}=1

c) N_{pr}=N_{sc}=1

d) N_{sc}=N_{se}=1

### View Answer

_{pr}=N

_{sc}=1 the equation for reynold’s analogy equals to equation by Chilton-colburn analogy.

10. What is the significance of fanning friction factor?

a) It is the ratio of pipe wall shear stress to velocity head

b) It is drag force divided by projected area and velocity head

c) It is the ratio of inertial forces to viscous force

d) It is the ratio of inertial force to surface tension force

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## Machine Design MCQ Set 5

1. Determine the rpm(n) of the shaft. diameter(d)=25 mm, cutting speed(cs)=50 m/min.

a) 636.9

b) 202.83

c) 10.615

d) none of the mentioned

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2. Determine the diameter(d) of the shaft in mm. rpm(n)=25 mm/revolution, cutting speed(cs)=100 mm/min.

a) 21.23

b) 405.47

c) 1273.2

d) none of the mentioned

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3. Determine the cutting speed(cs) of the shaft mm/min. diameter(d)=25 mm, rpm(n)=50 mm/revolution

a) 3.925

b) 1.25

c) 7.85

d) none of the mentioned

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4. If the diameter of the work surface before machining(d1) is 100 mm and diameter of the machined surface(d2) is 50 mm.

Then the depth of the cut is______ mm.

a) 50

b) 25

c) 15

d) none of the mentioned

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5. Find the metal removal rate from the given data (in mm*mm*mm/minute). cutting speed(cs) =50 mm/minute, depth of cut(d)=10mm, feed(f)= o.1 mm/revolution.

a) 50

b) 500

c) 5000

d) none of the mentioned

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6. Find the cutting speed from the given data (in mm/minute). metal removal rate(mrr) =50 mm*mm*mm/minute, depth of cut(d)=1mm, feed(f)= o.1 mm/revolution.

a) 50

b) 500

c) 5000

d) none of the mentioned

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7. Find the feed from the given data (in mm/revolution). cutting speed(cs) =50 mm/minute, depth of cut(d)=100mm, metal removal rate(mrr)= 10 mm/revolution.

a) 0.2

b) 0.02

c) 0.002

d) none of the mentioned

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8. Number of revolution = 50, rpm = 100. Find out the machining time.

a) 0.5

b) 2

c) 4

d) none of the mentioned

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9. The larger diameter of shaft is 125 mm and smaller diameter of the shaft is 95 mm. Find the taper. Assume that length of the job and taper is same.

a) 30

b) 15

c) 60

d) none of the mentioned

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10. Pitch of work piece threads=2, pitch of the lead screw threads=4.

Then, (driver gear/driven gear) =?

a) 2

b) 4

c) 0.5

d) none of the mentioned