Quiz:Mechanical Engineering 14 May 2020

Quiz: Mechanical Engineering
Exam: UPPSC AE
Topic: Thermal Engineering

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

Q1. Generally, runner blades are made of
(a) Cast iron
(b) Stainless steel
(c) Mild steel
(d) High carbon steel

Q2. Which one of the following represents energy in storage?
(a) Work
(b) Heat
(c) Energy
(d) Internal Energy

Q3. The convective heat transfer coefficient does not depend on
(a) Surface type
(b) Surface orientation
(c) Surface material
(d) Surface area

Q4. A polytropic process with n = -1 initiates with P = V = 0 and ends with P = 600 kPa and V = 0.01 m^3. The work done is
(a) 2 kJ
(b) 3 kJ
(c) 4 kJ
(d) 6 kJ

Q5. During steady state heat transport in a thin plate with uniform temperature, the nature of temperature distribution is
(a) Parabolic
(b) Logarithmic
(c) Linear
(d) Exponential

Q6. The ratio between emissive power and intensity of normal radiation is
(a) π
(b) π/2
(c) 2/π
(d) π/3

Q7. In a flow-field, streamlines and equipotential lines are
(a) Parallel to each other
(b) Perpendicular to each other
(c) Intersect each other at acute angle
(d) Intersect at obtuse angle

Q8. Which one of the following is an example of magneto fluid?
(a) Alcohol
(b) Water
(c) Liquid metal
(d) Ethylene Glycol

Q9. Which one of the following is an example of externally fired boiler?
(a) Lancashire boiler
(b) Cochran boiler
(c) Babcock and Wilcox boiler
(d) Scotch Marine boiler

Q10. Which one is the major advantage of centrifugal pump?
(a) Cost is low
(b) Efficiency is high
(c) Construction is simple
(d) Ease in use

Solutions

S1. Ans.(b)
Sol. Given that the turbine blades in a water turbine are constantly exposed to water and dynamic forces, they need to have high corrosion resistance and strength. The most common material used for the manufacturing of runner blades of turbines is stainless steel that have 17% to 20% chromium to increase stability of the film which improves aqueous corrosion resistance.

S2. Ans.(d)
Sol. Internal energy represents energy in storage in thermodynamics. It is due to the inter-molecular forces acting among the molecules of a gas.

S3. Ans.(d)
Sol. The convective heat transfer coefficient is a function of fluid thermo-physical properties, configuration of surface, material of surface but does not depend on area of surface.

S4. Ans.(b)
Sol. Work done in a polytropic process is defined as
W=(P1.V1-P2.V2)/(n-1)
W=(0-600×0.01)/(-1-1)
W=3 kJ

S5. Ans.(c)
Sol. During a steady state heat transport in a thin plate with uniform temperature, the nature of temperature distribution is Linear.

S6. Ans.(a)
Sol. Ratio of emissive power(E) and intensity (I) of thermal radiation is π.
E/I=π

S7. Ans.(b)
Sol. In a flow-field, streamlines and equipotential lines are perpendicular to each other.
Slope of Equipotential lines (m), dy/dx=u/v
Slope of Stream-lines(n),dy/dx=(-v)/u
For Equipotential lines and Stream-lines are perpendicular to each other,
m.n=-1

S8. Ans.(b)
Sol. Magneto-fluids are those fluids whose viscosity increases with magnetic field. e.g. mineral, silicone oils, kerosene, water etc.

S9. Ans.(c)
Sol. If, the firing of fuel is taking place outside the shell of boiler then it is called externally fired boiler and if, firing is taking place inside the shell of the boiler then it is called internally fired boiler. Examples of externally fired boilers are Babcock and Wilcox boiler, Stirling boiler etc.

S10. Ans.(c)
Sol. Major advantages of centrifugal pumps are their simplicity, compactness, weight saving and suitability for high speed prime movers.

Leave a comment

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