Quiz:Mechanical Engineering 26 June 2020

Quiz: Mechanical Engineering
Exam: ISRO (TECHNICAL ASST.)
Topic: Thermal

Each question carries 4 mark.
Negative marking: 1 mark
Time: 15 Minute

Q1. Which one of the following is not related to a compression ignition engine?
(a) Fuel pump
(b) Fuel injector
(c) Governor
(d) Carburetor

Q2. Gradually increasing temperature of flue gases at inlet to chimney for given steam output is a sign 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. If the sensible heating of air is taken place over a coil, then the coil efficiency in terms of B.P.F (Bypass factor) is
(a) B.P.F.-1
(b) 1+B.P.F.
(c) 1-B.P.F.
(d) B.P.F.+1

Q4. What type of rotary compressor is used in aeroplanes?
(a) Centrifugal type
(b) Radial flow type
(c) Axial flow type
(d) None of these

Q5. Indicator diagram of a reciprocating pump is a graph plotted between
(a) Pressure in cylinder vs swept volume
(b) Flow vs swept volume
(c) Pressure vs speed
(d) Flow vs speed

Q6. Following assumptions are made in Bernoulli’s equation:
(a) There is no loss of energy of the liquid flowing
(b) Only gravity force acts on the fluid
(c) The velocity of flow is uniform across any cross-section of the pipe
(d) All of these

Q7. In which of the following heat is transferred by radiation?
(a) Heating of building
(b) Cooling of parts in furnace
(c) Blast furnace
(d) Heat received by a person from fireplace

Q8. 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

Q9. Producer gas is obtained by
(a) Partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
(b) Passing steam over incandescent coke
(c) Carbonisation of bituminous coal
(d) Passing air and a large amount of steam over waste coal at about 700 Deg C

Q10. Which of the following law governs the heating of a gas at constant volume?
(a) Charles’ law
(b) Gay-Lussac law
(c) Boyle’s law
(d) Avogadro’s law

Solutions

S1. Ans (d)
Sol. Carburetor is used in Spark-ignition engine. It is a device which is used to form a mixture of air and fuel in a required proportion as per vehicle running conditions.

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 (c)
Sol. Coil efficiency or contact factor is defined as the fraction of air passing over the coil while contacting the coil surface.
If B.P.F. is bypass factor then coil efficiency or contact factor=1-B.P.F.

S4. Ans (c)
Sol. Axial flow type air compressor is used in aeroplanes. Axial flow type air compressor gives high head and low discharge flow.

S5. Ans (a)
Sol. Indicator diagram is plotted between mean effective pressure and swept volume of reciprocating engine.

S6. Ans (d)
Sol. Bernoulli’s equation is based on the following assumptions:
1.Steady flow
2. Incompressible fluid
3.No loss of energy
4.Only gravity force is in picture
5.Uniform velocity across any cross-section

S7. Ans (d)
Sol. Heat received by a person from fireplace is the case of heat transfer by radiation.

S8. Ans (b)
Sol. For an ideal reflector, the energy distribution at higher temperature is largely in the range of shorter wavelength.

S9. Ans (a)
Sol. Production of producer gas is done by partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast.

S10. Ans (b)
Sol. Gay-Lussac’s law states that at constant volume, absolute pressure of an ideal gas is proportional to the temperature of the gas.
i.e. P/T=Constant (At constant volume)

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