Quiz: Mechanical Engineering 30 July 2020

Quiz: Mechanical Engineering
Exam: UPPSC AE
Topic: Miscellaneous

Each question carries 3 mark.
Negative marking: 1 mark
Time: 10 Minute

Q1. The stress strain curve for cast iron during tensile test would exhibit
(a) A straight line
(b) A parabola
(c) A sudden break
(d) None of these

Q2. Gradually increasing temperature of flue gases at inlet to chimney for given steam output is an indication of
(a) Higher effectiveness of boiler
(b) Fouling of heat transfer surfaces
(c) Raising of steam temperature
(d) High calorific value of coal being burnt

Q3. Which of the following is true for martensite?
(a) It is a supersaturated solution of carbon in alpha iron
(b) It is a supersaturated solution of carbon beta iron
(c) It is a supersaturated solution of carbon gamma iron
(d) It is a supersaturated solution of carbon delta iron

Q4. The crystal structure of Titanium (Ti) at room temperature is
(a) Body-Centered Cubic (BCC)
(b) Face-Centered Cubic (FCC)
(c) Hexagonal Close-Packed (HCP)
(d) Simple Cubic (SC)

Q5. Which of the following purpose is served by the chills?
(a) Mixed in sand to enhance its collapsibility
(b) Metallic objects to provide very high heat extraction capability of sand mould
(c) Metallic objects to provide strength of sand mould
(d) Metallic objects to provide very low heat extraction capability of sand mould

Q6. Oxidizing flame is used for the welding of:
(a) Brass
(b) Mild steel
(c) Cast steel
(d) None of these

Q7. Which of the following is an application of merchant circle?
1. Improve the quality of a product
2. Find the principal stress and principal strain
3. Establish the shear angle relationship in machining
(a) only 1
(b) 1 and 2
(c) 1 and 3
(d) only 3

Q8. Which of the following is also known as three-dimensional cutting system?
(a) Oblique cutting
(b) Orthogonal cutting
(c) Both oblique and orthogonal cutting
(d) None of these

Q9. When we need to make the same parts again and again on a processing machine then which of the following machine is used?
(a) Center lathe
(b) Tool-room lathe
(c) Special purpose lathe
(d) Capstan lathe

Q10. For an ideal reflector, the energy distribution at higher temperature is largely in the range of
(a) Longer wavelength
(b) Shorter wavelength
(c) Remains same at all wavelengths
(d) No relation of wavelength with temperature

Solutions

S1. Ans.(c)
Sol. The stress -strain curve for cast iron during tensile test would exhibit a sudden break due to brittle failure.

S2. Ans (b)
Sol. If the temperature of flue gases increases from inlet to chimney outlet then it is a sign of fouling of heat transfer surfaces.

S3. Ans.(a)
Sol. A meta-stable phase of steel formed by transformation of austenite below a temperature 240℃ is known as martensite. It is an interstitial solid solution of carbon in α-iron.

S4. Ans.(c)
Sol. Titanium has hexagonal closed packed structure at room temperature. Generally, pure titanium can crystallize in two crystal structures: α titanium and β titanium. When it crystallizes at low temperatures (room temperature), the hexagonal close-packed (HCP) structure of alpha titanium is formed.

S5. Ans.(b)
Sol. There are certain areas in the casting that needs high heat extraction of heat due to variation in geometry of casting. For this purpose, we use chills that provide critical cooling rate.

S6. Ans.(a)
Sol. A slightly oxidizing flame is used in torch brazing of steel and cast iron. A stronger oxidizing flame is used in the welding of brass or bronze.

S7. Ans.(d)
Sol. According to Merchant circle relationship,
2ϕ+β-α=π/2
Or
ϕ=π/4+α/2-β/2
Here, ϕ is shear angle, α is rake angle and β is friction angle.

S8. Ans.(a)
Sol. When the cutting edge of the tool is inclined or making an angle (other than 90°) with the direction of feed, then it is called oblique cutting. This cutting is also called three-dimensional cutting because of force components in all three directions.

S9. Ans.(d)
Sol. A capstan machine is a processing machine used to make the same parts again and again. The cutting bits are mounted on a rotatable turret known as a capstan, which permits the client to rapidly change the introduction of the bits for slicing without needing to take off the first bit and afterward mount the second.

S10. Ans (b)
Sol. For an ideal reflector, the energy distribution at higher temperature is largely in the range of shorter wavelength.

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