Find real questions from previous competitive exam papers with answers and solutions.
Leave the keyword blank to browse saved questions for your selected exam, newest papers first. Add a keyword, year or topic to narrow the results.
Browse complete papersConsider an ideal Diesel cycle under cold air-standard assumptions (\( k = 1.4 \)), with compression ratio \( r = 18 \) and cut-off ratio \( \alpha = 2 \). The thermal efficiency is closest to ___.
48%
72%
55%
63%
Correct answer
48%
Identify the correct sequence of thermodynamic processes in an ideal Brayton cycle used in gas turbines.
Isothermal compression, constant-volume heat addition, isothermal expansion, constant-pressure heat rejection
Isentropic compression, constant-pressure heat addition, isentropic expansion, constant-pressure heat rejection
Constant-pressure compression, isentropic heat addition, constant-volume expansion, isentropic heat rejection
Isentropic compression, constant-volume heat addition, isothermal expansion, constant-pressure heat rejection
Correct answer
Isothermal compression, constant-volume heat addition, isothermal expansion, constant-pressure heat rejection
In a pumping station, \( 18,000m^3 \) of water per day is to be pumped from an intake well to a sedimentation tank under a static head of 21 m. The suction pipe length is 40 m, and the rising main length is 150 m. The diameter of both pipes is 0.5 m. The pumps operate in two 8-hour shifts. The coefficient of friction is 0.01, and the combined efficiency of motor and pump is 80%. Each pump has a capacity of 30 BHP.
Determine the number of pumps required.
2
3
4
5
Correct answer
2
A Pelton wheel having semi-circular buckets works under a head of 140 m. It runs at 600 r.p.m. The discharge through the nozzle is 500 L/s, and the wheel diameter is 0.6m. The coefficient of velocity of the jet is 0.98.
Find:
(a) Power available at the nozzle
(b) Hydraulic efficiency of the wheel
Power = 686.7 kW, \( \eta_h \) = 92.9%
Power = 612.5 kW, \( \eta_h \) = 85.0%
Power = 735.0 kW, \( \eta_h \) = 90.2%
Power = 686.7 kW, \( \eta_h \) = 88.5%
Correct answer
Power = 686.7 kW, \( \eta_h \) = 92.9%
Which of the following combinations of reasons best explains the widespread engineering use of ferrous alloys?
Abundant iron compounds, economical processing, and a wide property range
High melting point, ease of welding, and magnetic behaviour
Low-cost, alloying elements, corrosion resistance and hardness
Ease of recycling, low density, and thermal stability
Correct answer
Abundant iron compounds, economical processing, and a wide property range
Which microstructural constituents are explicitly stated to dominate low-carbon steels in their normal condition?
Austenite and bainite
Martensite and ferrite
Cementite and martensite
Ferrite and pearlite
Correct answer
Austenite and bainite
Why are plain medium carbon steels difficult to heat treat successfully in thick sections?
They possess low hardenability requiring rapid quenching
They transform completely to ferrite during cooling
They form excessive retained austenite
Alloy carbides prevent martensite formation
Correct answer
They possess low hardenability requiring rapid quenching
In the AISI SAE steel designation system, what do the last two digits of a four-digit steel number represent?
Manganese concentration multiplied by 100
Carbon concentration multiplied by 100
Carbon concentration multiplied by 1000
Manganese concentration multiplied by 1000
Correct answer
Manganese concentration multiplied by 100
Why can two steel alloys with identical carbon content exhibit identical hardness at the quenched end but significantly different hardness profiles inward?
Carbon content controls both surface and interior hardness
Quenching medium alters martensite hardness
Grain size variation dominates hardness near the surface
Alloying elements delay diffusional transformations during cooling
Correct answer
Carbon content controls both surface and interior hardness
During arc welding of steel, the welding voltage is 25V , and the current is 160A. The welding speed is 4 mm per second, and the cross-sectional area of the weld joint is \( 15mm^2 \). The heat required to melt steel is 9J per \( mm^3 \) and the heat transfer efficiency is 0.8. What is the melting efficiency of the welding process?
0.12
0.17
0.25
0.54
Correct answer
0.12