# Multiple choice question for engineering

## Set 1

1. Which fin yields the maximum heat flow per unit weight?

a) Straight triangular fin

b) Curved triangular fin

c) Parabolic fin

d) Hyperbolic fin

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2. Heat dissipation by every segment of the fin is

a) Sometimes same

b) Same

c) Not same

d) Sometimes same or sometimes not same

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3. “If a fin of a constant cross section is used, there would be wastage of material”. Chose the correct option

a) True

b) False

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4. Which one is true regarding parabolic fin?

a) It dissipates the minimum amount of heat at minimum material cost

b) It dissipates the minimum amount of heat at maximum material cost

c) It dissipates the maximum amount of heat at maximum material cost

d) It dissipates the maximum amount of heat at minimum material cost

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5. For parabolic fin, the curve follows which law?

a) y = C/x^{2}

b) y = C x^{4}

c) y = C x^{2}

d) y = C x^{1/2}

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^{2}or x = 4 y

^{2}.

6. The correction length for cylindrical fin is

a) L _{C} = L + d/4

b) L _{C} = 2 L + d/4

c) L _{C} = 3 L + d/4

d) L _{C} = 4 L + d/4

Where, d is the diameter

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^{2}/4.

7. Provision of fins on a given heat transfer surface will be more effective if there is

a) Fewer but thick fins

b) Large number of thick fins

c) Fewer but thin fins

d) Large number of thin fins

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_{C}brings about improvement in the effectiveness of fins.

8. The heat dissipation at any section of parabolic fin is given by

a) (t_{2} – t_{1}) (b) (δ)

b) k (t_{2} – t_{1}) (b) (δ)

c) k (t_{2} – t_{1}) (δ)

d) k (t_{2} – t_{1}) (b)

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_{x}(A

_{ X}) = k (t

_{2}– t

_{1}) (b) (δ).

9. An air cooled cylindrical wall is to be fitted with triangular fins of 3 cm thickness at base and 12 cm in height. The fins are made from stainless steel with density 8000 kg/m^{3} and thermal conductivity 17.5 W/m K. The wall temperature is 600 degree Celsius and the fin is exposed to an environment with t _{a} = 30 degree Celsius and h = 20 W/m^{2} K. What is the temperature distribution along the fin?

a) t = 10 + 250 I_{ 0} [6.056 (x)^{ 1/2}].

b) t = 20 + 250 I_{ 0} [6.056 (x)^{ 1/2}].

c) t = 30 + 250 I_{ 0} [6.056 (x)^{ 1/2}].

d) t = 40 + 250 I_{ 0} [6.056 (x)^{ 1/2}].

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_{0}= t – t

_{0}/t

_{ 0}– t

_{ a}= I

_{0 }[2 B (x)

^{ ½}]/ I

_{0 }[2 B (l)

^{ ½}]. Here B = (2 h l/k δ)

^{½ }= 3.028.

10. Consider the above problem, make calculations for the rate of heat flow per unit mass of fin material used

a) 126.53 W/kg

b) 154.76 W/kg

c) 134.87 W/kg

d) 165.46 W/kg

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^{ ½ }α

_{0 }I

_{1}[2 B (L)

^{½}/ I

_{0}[2 B (L)

^{½}= 1822 W. Mass of fin per meter width = 14.4 kg. Therefore rate of heat flow per unit mass = 1822/14.4 = 126.53 W/kg.

## Set 2

1. The distribution of radiant energy is non uniform with respect to

a) Wavelength

b) Direction

c) Both wavelength and direction

d) Time

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2. “Spatial distribution is also known as directional distribution”. Choose the correct option

a) True

b) False

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3. Of the radiant energy 350W/m^{2} incident upon a surface 250W/m^{2} is absorbed, 60W/m^{2} is reflected and the remainder is transmitted through the surface. Workout the value for absorptivity for the surface material

a) 0.123

b) 0.714

c) 0.684

d) 0.386

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4. Thermal radiation strikes a surface which has a reflectivity of 0.55 and transmissivity of 0.032. A quantity known as flux is found out to be 95 W/m ^{2}. Determine the rate of incident flux.

a) 123.34 W/m^{2}

b) 333.37 W/m^{2}

c) 122.27 W/m^{2}

d) 227.27 W/m^{2}

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^{2}.

5. What is the wavelength for visible light?

a) 3.9 * 10^{ -1 }to 7.8 * 10^{ -1} micron meter

b) 4.9 * 10^{ -1 }to 7.8 * 10^{ -1} micron meter

c) 5.9 * 10^{ -1 }to 7.8 * 10^{ -1} micron meter

d) 6.9 * 10^{ -1 }to 7.8 * 10^{ -1} micron meter

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6. Radiant energy with an intensity of 800 W/m^{2} strikes a flat plate normally. The absorptivity is thrice the reflectivity and twice the transmissivity. Determine the rate of absorption

a) 236.40 W/m^{2}

b) 336.40 W/m^{2}

c) 436.40 W/m^{2}

d) 536.40 W/m^{2}

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^{2}.

7. A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m ^{2} K, workout the reflectivity of the plate

a) 0.35

b) 0.45

c) 0.55

d) 0.65

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8. On clear night there is radiation from earth’s surface to the space. On such a night, the water particles on the plant leaves radiate to the sky whose temperature may be taken as 200 K. The water particles receive heat by convection from the surrounding air, the convection heat transfer coefficient has a value of 30 W/m^{2} K. If the water should not freeze, make calculations for the air temperature

a) 280.474 K

b) 345.645 K

c) 123.456 K

d) 874.387 K

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9. “Isothermal furnaces, with small apertures, approximate a black body and are frequently used to calibrate heat flux gauges”. Chose the correct answer

a) True

b) False

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10. “A surface element emits radiation in all directions, the intensity of radiation is however same in different directions. Choose the correct answer

a) True

b) False

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## Set 3

1. Clamp coupling employ bolts.

a) True

b) False

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2. Entire torque is transmitted by friction in the clamp coupling.

a) True

b) False

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3. Does shaft has to be shifted i axial direction to remove clamp coupling.

a) Yes

b) No

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4. If shaft diameter is 40mm, calculate the diameter of sleeves in clamp coupling.

a) 100mm

b) 80mm

c) 60mm

d) 40mm

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5. If shaft diameter is 40mm, calculate the length of sleeves in clamp coupling.

a) 80mm

b) 140mm

c) 100mm

d) 120mm

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6. If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the tensile force on each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m.

a) 51234.4N

b) 45968.3N

c) 41666.7N

d) None of the listed

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7. If 8 bolts are emplaced in a clamp coupling with shaft diameter 80mm d, calculate the diameter of each bolt if coefficient of friction is 0.3 and torque transmitted is 4000N-m. Permissible tensile stress is 80N/mm².

a) 27mm

b) 25mm

c) 23mm

d) 21mm

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8. Power is transmitted by only in rigid flange coupling.

a) True

b) False

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9. If shaft diameter is 60mm, how many bolts are recommended for rigid flange coupling?

a) 2

b) 3

c) 4

d) 5

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10. Determine the diameter of the bolts used in rigid flange coupling if transmitted torque is 270N-m, pitch circle diameter=125mm and four bolts are emplace in the coupling. Permissible shear stress in the bolts is 70N/mm².

a) 3.8mm

b) 3.6mm

c) 4.4mm

d) 4mm

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11. The hub is treated as a solid shaft while calculating torsional shear stress in the hub.

a) True

b) False

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12. Find the shear stress in a flange at the junction of hub in rigid flanged coupling if torsional moment is 2980N-m and diameter of hub being 125mm. Also the thickness of flange is 25mm.

a) 6.77N/mm²

b) 10.24N/mm²

c) 4.84N/mm²

d) 4.22N/mm²

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13. If shaft diameter is 30mm and number of pins emplaced are 6, then the diameter of the pin will be?

a) 6.4mm

b) 5.6mm

c) 6.1mm

d) 5.9mm

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14. Calculate the force acting on the each pin in flexible coupling if torque transmitted is 397N-m and PCD=120mm with number of pins 6.

a) 1400.3N

b) 1102.8N

c) 1320.3N

d) None of the listed

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## Set 4

Answer the question 1-7 with respect to figure 1

1. The two welds shown in the figure experience equal resisting force?

a) True

b) False

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2. The moment of forces about the CG is ?

a) Zero

b) Infinite

c) P₁y₁+P₂y₂

d) None of the listed

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3. Which equations can be used to find the resisting force in the two welds?

a) P=P₁+P₂

b) P₁+P₂=0

c) Both P=P₁+P₂ and P₁y₁=P₂y₂

d) P₁y₁=P₂y₂

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4. For the following welded joint l₁y₁=l₂y₂.

a) True

b) False

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5. Find the total length of weld required to with stand the load of 100kN. Permissible shear stress in weld is 70kN/mm².

a) None of the listed

b) 101.03mm

c) 202.06mm

d) 30309mm

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6. Find the length of weld 2 required to with stand the load of 100kN. Permissible shear stress in weld is 70kN/mm².

a) None of the listed

b) 102.22mm

c) 132.4mm

d) 70.16mm

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7. Find the length of weld 1 required to with stand the load of 100kN. Permissible shear stress in weld is 70kN/mm².

a) None of the listed

b) 102.22mm

c) 132.4mm

d) 70.16mm

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Figure 2

Answer the following questions with respect to figure 2

8. The following welded joint is an example of

a) Eccentric Load in plane of welds

b) Axial load in plane of welds

c) Axial load in plane perpendicular to plane of welds

d) None of the mentioned

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9. What kind of stresses does the welded joint undergo?

a) Torsional shear stress

b) Direct shear stress

c) Direct and torsional shear stress

d) None of the listed

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10. While considering moment of inertia for calculating torsional shear stress, J=I(xx) + I(yy), which of the following can be neglected in context with the following figure?

a) I(xx)

b) I(yy)

c) Both I(xx) and I(yy)

d) None of the listed

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11. Calculate the direct shear stress in the welds by ignoring torsional shear stress if P=8kN and thickness of weld is 5mm.

a) None of the listed

b) 12.33N/mm

c) 13.33N/mm

d) 14.33N/mm

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12. Determine the torsional shear stress in the welds if P=8kN and thickness of the welds is assumed t.

a) None of the listed

b) 456.34/t

c) 543.13/t

d) 589.31/t

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13. Find the thickness of the weld if P=8kN and permissible shear stress in the welds is 100N/mm²

a) 4mm

b) 5mm

c) 6mm

d) 7mm

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## Set 5

1. The various cutting tool materials used are:

a) high speed steels

b) cast cobalt alloys

c) carbides

d) all of the mentioned

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2. High speed steels are suitable for making

a) high positive rake angle tools

b) interrupted cuts

c) machine tools with ow stiffness that are subject to vibration

d) all of the mentioned

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3. ___________ improves toughness, wear resistance, and high temperature strength.

a) Chromium

b) vanadium

c) Tungsten

d) None of the mentioned

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4. _____________ contains nickel molybdenum matrix.

a) Chromium

b) Titanium carbide

c) Tungsten

d) None of the mentioned

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5. Coating materials used are

a) titaniun nitride

b) titanium carbide

c) titanium carbonitride

d) all of the mentioned

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_{2}O

_{3}).

6. Characteristics of coated cutting tools are:

a) high hardness

b) chemical stability

c) low thermal conductivity

d) all of the mentioned

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7. Ceramic tools are fixed ti tool body by

a) soldering

b) brazing

c) welding

d) clamping

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8. The carbide tools operating at very low cutting speeds

a) reduces tool life

b) increases tool life

c) have no effect on tool life

d) spoils the work piece

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9. High speed steel tools retain their hardness upto a temperature of

a) 250^{0}

b) 350^{0}

c) 500^{0}

d) 900^{0}

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10. The trade name of a non ferrous cast alloy composed of cobalt, chromium and tungsten is called

a) ceramic

b) stellite

c) diamond

d) cemented carbide