Quiz: Mechanical Engineering 02 July 2020

Quiz: Mechanical Engineering
Exam: UPPSC AE
Topic: Miscellaneous

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

Q1. What is the main function of chaplets?
(a) It ensures directional solidification just like chills
(b) It provides efficient venting
(c) It supports the core
(d) It joins lower and upper parts of the moulding sand

Q2. Graphite mould are generally used for continuous casting method because
(a) The metals wet the mould slightly
(b) They are self-lubricating
(c) Only a small amount of lubricating oil is required
(d) They are comparatively cheaper

Q3. The soldering iron is heated in gas flame until
(a) the bit is the red hot
(b) the coating of Borax on the bit turns black
(c) the gas flame appears orange in the colour
(d) the gas flame appears green in the colour

Q4. When turning a long shaft on a lathe, its bending can be prevented by:
(a) running the shaft at low speed
(b) using sturdy machine
(c) using high speed
(d) using steady rest

Q5. As per Indian standard specifications, a plain carbon steel designated as 40C8 contains ___________ % of carbon.
(a) 0.4 to 0.6
(b) 0.04
(c) 0.6 to 0.8
(d) 0.35 to 0.45

Q6. For which of the following products, the LD converter is used?
(a) steel
(b) polythene
(c) graphite
(d) cast iron

Q7. Which of the following is a non-quasi-static process?
(a) Free expansion of a gas
(b) Expansion of a gas in a cylinder under constant pressure
(c) Rapid compression of a gas in a cylinder
(d) Gradual compression of a gas in a cylinder

Q8. Which of the following statements is incorrect regarding a four-stroke engine as compared to a two-stroke engine?
(a) It requires a heavier foundation
(b) It can be easily started
(c) More cooling time is available
(d) It occupies more space

Q9. What is the unsteady to and fro motion of the fluid that causes pulsation in the engine compressor known as?
(a) Compressing
(b) Pulsing
(c) Choking
(d) Surging

Q10. Radius of curvature of a stressed beam and modulus of elasticity
(a) are directly proportional
(b) are inversely proportional
(c) are curvilinear related
(d) have unpredictable relationship

Solutions

S1. Ans.(c)
Sol. Chaplets are used to position and support the core.

S2. Ans.(b)
Sol. Graphite is a self-lubricating which creates low friction between the mould surface and the solidifying metal; ensuring smooth extraction of the casting without cracks.

S3. Ans.(a)
Sol. A soldering iron is a hand tool used in soldering. It supplies heat to melt solder so that it can flow into the joint between two work pieces. The soldering iron is heated in gas flame until it becomes red.

S4. Ans.(d)
Sol. When turning a long shaft on a lathe, its bending can be prevented by using steady rest.

S5. Ans.(d)
Sol. As per Indian standard specifications, a plain carbon steel designated as 40C8 contains 0.35 to 0.45 % carbon.

S6. Ans.(a)
Sol. Basic oxygen steel-making process also known as Linz–Donawitz-steel-making or the oxygen converter process. This is used for steel products.

S7. Ans.(a)
Sol. Free expansion of a gas is a non-quasi-static or irreversible process.

S8. Ans.(b)
Sol. Two stroke engine is easier to start when as compared to four stroke engines. Four-stroke engines require two complete turns of the crankshaft to make a power stroke, compared to the single turn necessary in a two-stroke engine. Cold starting is also easier in two stroke engines i.e. why it is used in snowmobiles.

S9. Ans.(d)
Sol. There is an unstable limit of operation of centrifugal and axial flow compressor, known as surging. Surging is caused due to unsteady, periodic and reversal of flow through the compressor when the compressor has to operate at less mass flow rate than a predetermined value.

S10. Ans.(a)
Sol. From bending-moment equation,
M/I=σ/Y=E/R
So,
E∝R

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