Quiz: Mechanical Engineering 13 July 2020

Quiz: Mechanical Engineering
Exam: UPSSSC JE
Topic: Miscellaneous

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. What is the temperature at which a system goes under a reversible isothermal process without heat transfer?
(a) Absolute zero temperature
(b) Critical temperature
(c) Reversible temperature
(d) Boiling temperature

Q2. The property of a working system which changes as the heat is supplied to the working fluid in a reversible manner is known as-
(a) entropy
(b) enthalpy
(c) external energy
(d) internal energy

Q3. Which of the following cycles is not a reversible cycle?
1.Carnot
2.Ericsson
3.Stirling
4.Joule
(a) only A
(b) only A and B
(c) only C
(d) None of these

Q4. An engine indicator is used to determine the following
(a) Speed
(b) Temperature
(c) Indicative power
(d) None of these

Q5. Function of blow-down cock of a boiler is
(a) to maintain water level by draining excess water
(b) to empty the water drum of the boiler
(c) to remove sludge and sediments collected in drum
(d) to blow-off steam to maintain safe pressure

Q6. In a composite bar, the resultant strain produced will be-
(a) same as the strain produced in the bar
(b) sum of the strain produced by the individual bars
(c) same as the stress produced in each bar
(d) difference of strain produced in individual bars

Q7. Choose the correct option for the buckling load in a column to have the maximum value.
(a) Both ends of the column are fixed
(b) Both ends of the column are hinged
(c) One end of the column is clamped and the other end is free
(d) One end of the column is hinged and the other end is free

Q8. Which one of the following is the type of completely constrained motion?
(a) shaft in a circular hole
(b) shaft in a foot step bearing
(c) square bar in a square hole
(d) both shaft with collars in a circular hole and shaft in a foot step bearing

Q9. If a stiffer spring is used in Hartnell governor, then the governor will be-
(a) more sensitive
(b) less sensitive
(c) sensitivity remains unaffected
(d) isochronous

Q10. A fluid in which resistance to deformation is independent of the shear stress is called-
(a) Bingham plastic fluid
(b) Pseudo plastic fluid
(c) Dilatant fluid
(d) Newtonian fluid

Solutions

S1. Ans (a)
Sol. According to definition of Kelvin-scale, a system goes under a reversible isothermal process without heat transfer at the absolute temperature.

S2. Ans (a)
Sol. We know that
Change in entropy in reversible process (∆S)=∆Q/T
If heat is transferred in to the system then entropy change is positive and if heat is transferred out of the system then entropy change is negative.

S3. Ans (d)
Sol. Carnot, Ericsson, Stirling and Joule all are reversible cycles because all of the processes involved in these cycles are reversible.

S4. Ans (c)
Sol. An engine indicator diagram is a graph which is drawn between pressure and piston displacement through an engine stroke. Its area tells about the indicative power of the engine.

S5. Ans (c)
Sol. Due to continuous heating up and boiling of the water, sludge and sediments are collected at the inside walls of the tubes in case of water tube boilers. So, we use blow-down cock for periodical cleaning of the boiler to avoid overpressure and choking in the tubes.

S6. Ans (a)
Sol. In a composite bar, the resultant strain produced will be same as the strain produced in the bar from the compatibility equation.

S7. Ans (a)
Sol. We know that
Buckling load = (π^2 EI)/L^2
For both ends fixed effective length (L) = l/2
So, Buckling load = (4π^2 EI)/l^2 (Maximum)

S8. Ans (c)
Sol. When the components of a pair can have motion only in one direction with respect to each other then it is called completely constrained motion. E.g. square bar in a square hole etc.

S9. Ans (b)
Sol. If a stiffer spring is used in Hartnell governor, then the governor will be less sensitive. It is because the motion of the stiffer spring in response to change in speed of the engine is difficult.

S10. Ans (d)
Sol. A fluid in which resistance to deformation is independent of the shear stress is called Newtonian fluid. Here, resistance to deformation refers to viscosity of fluid.

Leave a comment

Your email address will not be published. Required fields are marked *