Quiz:Mechanical Engineering 9 June 2020

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

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

Q1. For a given set of operating pressure limits of a Rankine cycle the highest efficiency occurs for
(a) Saturated cycle
(b) Superheated cycle
(c) Reheat cycle
(d) Regenerative cycle

Q2. High API gravity of fuel means:
(a) Lower Diesel index
(b) Lower Brake specific fuel consumption
(c) Lower heat of combustion
(d) Lower ignition quality

Q3. A refrigerant should have:
(a) High specific heat of liquid
(b) High boiling point
(c) High latent heat of vaporization
(d) Low critical temperature

Q4. Lumped heat capacity approach of transient heat conduction analysis is used:
(a) For bodies of very high conductive resistance
(b) When temperature variation throughout the body is very high
(c) When temperature variation throughout the body is very low
(d) For Biot number > 10

Q5. What happens to the liquid level, when a small diameter tube is inserted into a liquid whose contact angle is 125°?
(a) Liquid level in the tube will fall first and then rise.
(b) Liquid level in the tube falls.
(c) Liquid level in the tube remains constant
(d) Liquid level in the tube rises

Q6. A Rotameter can be used
(a) Only in vertical orientation (direction)
(b) Only in horizontal orientation (direction)
(c) In any orientation (direction)
(d) For zero orientation (direction)

Q7. Two simply supported beams of equal lengths, cross sectional areas and section moduli, are subjected to the same concentrated load at its mid-length. One beam is made of steel and other is made of Aluminium. The maximum bending stress induced will be in
(a) Steel beam
(b) Aluminium beam
(c) Both beams of equal magnitude
(d) The beams according to their Elastic moduli magnitude

Q8. In clamp coupling, power is transmitted by means of-
(a) Friction force
(b) Shear resistance
(c) Crushing resistance
(d) Tear resistance

Q9. The primary cause for deflection of arc during arc welding is………..
(a) Hydro static field
(b) Magnetic field
(c) Explosive field
(d) Wind velocity field

Q10. A bearing material should not possess the characteristic of high…………
(a) coefficient of friction
(b) hardness
(c) melting point
(d) thermal conductivity

Solutions

S1. Ans (d)
Sol. For given operating pressure limits in a Rankine cycle, the highest efficiency occurs for Regenerative cycle. It is because mean temperature of heat addition increases in the regenerative cycle.

S2. Ans (b)
Sol. API stands for American Petroleum institute. API gravity is a measure of how heavy or light a petroleum liquid is as compared to water. High API gravity of fuel represents lower brake specific fuel consumption.

S3. Ans (c)
Sol. There are following properties of a good refrigerant:
1.Low boiling point.
2.Low freezing point
3.High latent heat of vaporization
4.Low viscosity
5.Low specific volume
6.High critical temperature

S4. Ans (c)
Sol. Lumped heat capacity approach of transient heat conduction analysis is used when conductive resistance of the body is negligible and hence, the variation in temperature throughout the body is also negligible.

S5. Ans (b)
Sol. When angle of contact is more than 90°, then liquid level will fall in the tube. In contradiction, when angle of contact is less than 90°, then liquid level will rise in the tube.

S6. Ans (a)
Sol. A Rotameter is a device that measures the volumetric flow rate of a fluid in a closed tube. It can be used in only vertical orientation.

S7. Ans (c)
Sol. We know that bending-moment equation,
M/I=σ/y
σ=My/I
Since, maximum bending moment and section modulus of both the beams are same, then maximum bending stress induced in both the beams will be same.

S8. Ans (a)
Sol. The main mean of power transmission in clamp coupling is frictional force.

S9. Ans (b)
Sol. The primary cause for deflection of arc, during arc welding is magnetic field called arc blow. Arc blow is mainly, the deflection of electric arc from its regular path.

S10. Ans (a)
Sol. A good bearing material should possess following properties:
1.Low coefficient of friction.
2.High hardness
3.High melting point
4.High thermal conductivity

 

 

 

 

 

 

 

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