A heat engine receives 500 kJ of heat and rejects 300 kJ. Its thermal efficiency is
A. 66.7 percent
B. 25 percent
C. 60 percent
D. 40 percent
View answer and explanation
Correct Option: D
W = 500 − 300 = 200 kJ. η = 200/500 = 0.4.
Q54Mechanical Engineering (SSC JE)
Easy
A refrigerator has a COP of 4. When the same machine is used as a heat pump, its COP is
A. 5
B. 3
C. 0.25
D. 4
View answer and explanation
Correct Option: A
COP(heat pump) = COP(refrigerator) + 1, because Q_H = Q_L + W.
Q55Mechanical Engineering (SSC JE)
Easy
Heat of 600 kJ is added reversibly to a system at a constant temperature of 300 K. The change of entropy of the system is
A. 180 kJ/K
B. 0.5 kJ/K
C. 200 kJ/K
D. 2 kJ/K
View answer and explanation
Correct Option: D
ΔS = Q/T = 600/300 = 2 kJ/K.
Q56Mechanical Engineering (SSC JE)
Hard
Wet steam has a dryness fraction of 0.9. If hf = 500 kJ/kg and hfg = 2000 kJ/kg, its enthalpy is
A. 2000 kJ/kg
B. 1800 kJ/kg
C. 2500 kJ/kg
D. 2300 kJ/kg
View answer and explanation
Correct Option: D
h = hf + x hfg = 500 + 0.9 × 2000 = 2300 kJ/kg.
Q57Mechanical Engineering (SSC JE)
Medium
Among the Otto, Diesel and Dual cycles with the same compression ratio and the same heat input, the air standard efficiency is highest for the
A. Otto cycle
B. None; all three are equal
C. Dual cycle
D. Diesel cycle
View answer and explanation
Correct Option: A
For the same compression ratio, Otto > Dual > Diesel, because all the heat in the Otto cycle is added at constant volume (at the highest mean temperature).
Q58Mechanical Engineering (SSC JE)
Easy
According to Dalton’s law of partial pressures, the total pressure of a gas mixture is
A. the sum of the partial pressures of its components
B. the product of the partial pressures of its components
C. the average of the partial pressures
D. equal to the highest partial pressure
View answer and explanation
Correct Option: A
Each ideal gas in the mixture exerts the pressure it would exert if it alone occupied the volume.
Q59Mechanical Engineering (SSC JE)
Easy
A polytropic process pvⁿ = constant with n = 0 is
A. an isobaric (constant pressure) process
B. an isochoric process
C. an isentropic process
D. an isothermal process
View answer and explanation
Correct Option: A
n = 0 gives p = constant. n = 1 is isothermal, n = γ is isentropic and n = ∞ is isochoric.
Q60Mechanical Engineering (SSC JE)
Hard
An ideal gas expands adiabatically from p1V1 = 500 kJ to p2V2 = 300 kJ. With γ = 1.4, the work done by the gas is
The specific speed of a hydraulic turbine, in terms of the speed N, power P and head H, is
A. N√Q / H^(3/4)
B. N√P / H^(3/4)
C. N P / H²
D. N√P / H^(5/4)
View answer and explanation
Correct Option: D
For turbines Ns = N√P / H^(5/4). The expression N√Q / H^(3/4) is the specific speed of a pump.
Q68Mechanical Engineering (SSC JE)
Easy
If the speed of a centrifugal pump is doubled, the head produced (by the affinity laws) becomes
A. 2 times
B. 16 times
C. 8 times
D. 4 times
View answer and explanation
Correct Option: D
H ∝ N² D², so doubling N makes H four times, Q twice and power eight times.
Q69Mechanical Engineering (SSC JE)
Medium
A Pelton wheel gives maximum efficiency when the bucket speed is
A. half the jet speed
B. equal to the jet speed
C. double the jet speed
D. one-third of the jet speed
View answer and explanation
Correct Option: A
For symmetrical buckets turning the jet through 180°, the maximum hydraulic efficiency occurs at u = v/2.
Q70Mechanical Engineering (SSC JE)
Easy
For an orifice, Cc = 0.62 and Cv = 0.97. The coefficient of discharge is
A. 0.60
B. 0.62
C. 0.97
D. 1.59
View answer and explanation
Correct Option: A
Cd = Cc × Cv = 0.62 × 0.97 = 0.601.
Q71Mechanical Engineering (SSC JE)
Hard
The Net Positive Suction Head (NPSH) available at the pump inlet is
A. the total head at the suction above the vapour pressure head of the liquid
B. the delivery head minus the suction head
C. the static head of the liquid
D. the head lost in friction in the delivery pipe
View answer and explanation
Correct Option: A
It must exceed the required NPSH of the pump to avoid cavitation.
Q72Mechanical Engineering (SSC JE)
Hard
Air at 300 K flows at 100 m/s (cp = 1005 J/kg·K). The stagnation temperature is about
A. 300 K
B. 310 K
C. 350 K
D. 305 K
View answer and explanation
Correct Option: D
T0 = T + V²/2cp = 300 + 10 000 / 2010 = 300 + 4.98 ≈ 305 K.
Q73Mechanical Engineering (SSC JE)
Medium
The excess pressure inside a soap bubble of diameter d and surface tension σ is
A. 4σ / d
B. σ / d
C. 2σ / d
D. 8σ / d
View answer and explanation
Correct Option: D
A bubble has two surfaces, so Δp = 4σ/R = 8σ/d. A liquid droplet has one surface, with Δp = 4σ/d.
Q74Mechanical Engineering (SSC JE)
Easy
The capillary rise of a liquid in a glass tube is
A. proportional to the diameter of the tube
B. inversely proportional to the diameter of the tube
C. proportional to the square of the diameter
D. independent of the diameter of the tube
View answer and explanation
Correct Option: B
h = 4σ cos θ / (ρ g d).
Q75Mechanical Engineering (SSC JE)
Medium
In fully turbulent flow through a rough pipe, the friction factor depends mainly on
A. the relative roughness of the pipe
B. the Reynolds number only
C. the Froude number
D. the Mach number
View answer and explanation
Correct Option: A
At high Re the viscous sub-layer is smaller than the roughness, so f becomes independent of Re and depends on ε/D alone.
Q76Mechanical Engineering (SSC JE)
Easy
The flow to a Pelton wheel is regulated by
A. guide vanes
B. a spear (needle) valve in the nozzle
C. a draft tube
D. adjustable runner blades
View answer and explanation
Correct Option: B
The spear moves in and out of the nozzle, which changes the jet area while the head and velocity stay the same.
Q77Mechanical Engineering (SSC JE)
Hard
A composite wall has two layers: k1 = 1 W/m·K, thickness 0.1 m, and k2 = 0.5 W/m·K, thickness 0.1 m. The temperature difference across the wall is 60 °C. The heat flux is
In a counterflow heat exchanger, hot fluid cools from 100 °C to 60 °C and cold fluid heats from 30 °C to 50 °C. The LMTD is about
A. 40.0 °C
B. 50.0 °C
C. 30.0 °C
D. 39.2 °C
View answer and explanation
Correct Option: D
ΔT1 = 100 − 50 = 50 °C and ΔT2 = 60 − 30 = 30 °C. LMTD = (50 − 30)/ln(50/30) = 20/0.511 = 39.2 °C.
Q79Mechanical Engineering (SSC JE)
Easy
A lumped capacitance analysis of transient conduction is valid when the Biot number is
A. less than 0.1
B. greater than 10
C. greater than 100
D. equal to 1
View answer and explanation
Correct Option: A
Bi = hL/k < 0.1 means that the internal resistance of the solid is small, so its temperature is nearly uniform.
Q80Mechanical Engineering (SSC JE)
Medium
In the effectiveness-NTU method of heat exchanger analysis, NTU is defined as
A. UA / Cmin
B. UA × Cmin
C. Cmin / UA
D. Cmax / Cmin
View answer and explanation
Correct Option: A
NTU is the number of transfer units, the ratio of the thermal size UA to the smaller heat capacity rate.
Q81Mechanical Engineering (SSC JE)
Easy
The Prandtl number is defined as
A. ρ V L / μ
B. μ cp / k
C. g β ΔT L³ / ν²
D. h L / k
View answer and explanation
Correct Option: B
It is the ratio of momentum diffusivity to thermal diffusivity.
Q82Mechanical Engineering (SSC JE)
Hard
According to Wien’s displacement law, the peak emission of a black body at 1449 K occurs at a wavelength of about (λmax·T = 2898 μm·K)
A. 2 μm
B. 4 μm
C. 1 μm
D. 0.5 μm
View answer and explanation
Correct Option: A
λmax = 2898 / 1449 = 2 μm.
Q83Mechanical Engineering (SSC JE)
Hard
A material has E = 200 GPa and Poisson’s ratio 0.25. The modulus of rigidity is
A. 66.7 GPa
B. 80 GPa
C. 160 GPa
D. 100 GPa
View answer and explanation
Correct Option: B
G = E / [2(1 + ν)] = 200 / 2.5 = 80 GPa.
Q84Mechanical Engineering (SSC JE)
Hard
A steel bar and a copper bar, each of area 100 mm², share a total axial load of 30 kN in parallel (Es = 200 GPa, Ec = 100 GPa). The load carried by the steel is
A. 15 kN
B. 10 kN
C. 30 kN
D. 20 kN
View answer and explanation
Correct Option: D
Both bars have the same strain, so the loads share in proportion to AE: 2 : 1. Steel takes 2/3 × 30 = 20 kN.
Q85Mechanical Engineering (SSC JE)
Medium
The maximum deflection of a simply supported beam of span L carrying a uniformly distributed load w per unit length is
A. wL⁴ / 192EI
B. 5wL⁴ / 384EI
C. wL⁴ / 8EI
D. wL³ / 48EI
View answer and explanation
Correct Option: B
The standard result for a full span UDL on a simply supported beam is 5wL⁴/384EI. The value wL⁴/8EI is for a cantilever.
Q86Mechanical Engineering (SSC JE)
Easy
Two solid shafts of the same material and length have diameters in the ratio 2 : 1. The ratio of the torques they can transmit at the same maximum shear stress is
A. 16 : 1
B. 2 : 1
C. 8 : 1
D. 4 : 1
View answer and explanation
Correct Option: C
T = π τ d³ / 16, so T ∝ d³, giving 2³ : 1 = 8 : 1.
Q87Mechanical Engineering (SSC JE)
Hard
At a point, σx = 100 MPa, σy = 0 and τxy = 50 MPa. The maximum principal stress is
A. the least of the shearing, tearing and crushing strengths to the strength of the solid plate
B. the number of rivets to the pitch
C. the rivet strength to the plate thickness
D. the strength of the solid plate to the strength of the joint
View answer and explanation
Correct Option: A
The weakest failure mode of the joint decides its strength, which is then compared with the unriveted plate.
Q105Mechanical Engineering (SSC JE)
Hard
A parallel fillet weld of size s = 8 mm has an allowable shear stress of 100 N/mm². The load per mm length is about
A. 400 N/mm
B. 800 N/mm
C. 565.6 N/mm
D. 1131 N/mm
View answer and explanation
Correct Option: C
Throat = 0.707 s = 5.656 mm. Load per mm = 5.656 × 100 = 565.6 N.
Q106Mechanical Engineering (SSC JE)
Easy
The Lewis equation is used to estimate
A. the pitch of a chain drive
B. the bending (beam) strength of a gear tooth
C. the wear strength of a gear tooth
D. the tension of a belt
View answer and explanation
Correct Option: B
It treats a gear tooth as a cantilever beam of uniform strength.
Q107Mechanical Engineering (SSC JE)
Medium
The Sommerfeld number in the design of journal bearings is
A. a dimensionless parameter involving viscosity, speed, pressure and clearance ratio
B. the number of rolling elements
C. the ratio of load to speed
D. a measure of the hardness of the bearing metal
View answer and explanation
Correct Option: A
S = (μN/p)(r/c)². It decides the bearing operating condition, such as the minimum film thickness.
Q108Mechanical Engineering (SSC JE)
Easy
Two springs of stiffness 100 N/mm each are connected in series. The equivalent stiffness is
A. 25 N/mm
B. 50 N/mm
C. 100 N/mm
D. 200 N/mm
View answer and explanation
Correct Option: B
1/k = 1/100 + 1/100 = 1/50, so k = 50 N/mm. In parallel it would be 200 N/mm.
Q109Mechanical Engineering (SSC JE)
Hard
Among the fatigue failure criteria, the Soderberg line
A. ignores the mean stress
B. uses the ultimate strength and is the least conservative
C. uses the yield strength and is the most conservative
D. ignores the alternating stress
View answer and explanation
Correct Option: C
The Soderberg line joins the endurance limit and the yield strength, so it lies below the Goodman and Gerber lines.
Q110Mechanical Engineering (SSC JE)
Easy
A cotter joint is used to connect two rods which are subjected to
A. bending only
B. axial tension or compression
C. a rotating bending load
D. torsion only
View answer and explanation
Correct Option: B
The tapered cotter is driven through slots in the rod ends, so the joint can be assembled and dismantled easily.
Q111Mechanical Engineering (SSC JE)
Hard
A single cylinder four-stroke engine has a bore of 100 mm, stroke of 150 mm, mean effective pressure of 6 bar and runs at 1200 rpm. The indicated power is about
A. 70.7 kW
B. 3.5 kW
C. 14.1 kW
D. 7.07 kW
View answer and explanation
Correct Option: D
A = π × 0.1²/4 = 0.007854 m². Work per cycle = 6 × 10⁵ × 0.007854 × 0.15 = 707 J. Cycles per second = 600/60 = 10. IP = 7.07 kW.
Q112Mechanical Engineering (SSC JE)
Easy
An engine has a brake power of 6 kW and an indicated power of 7.5 kW. Its mechanical efficiency is
A. 80 percent
B. 125 percent
C. 75 percent
D. 90 percent
View answer and explanation
Correct Option: A
ηm = BP/IP = 6/7.5 = 0.8.
Q113Mechanical Engineering (SSC JE)
Medium
The volumetric efficiency of an engine is the ratio of
A. the indicated power to the brake power
B. the swept volume to the clearance volume
C. the air-fuel ratio to the stoichiometric ratio
D. the actual volume of air drawn in to the swept volume (at intake conditions)
View answer and explanation
Correct Option: D
It shows how well the engine breathes. It falls with throttling, high intake temperature and restricted valves.
Q114Mechanical Engineering (SSC JE)
Easy
The specific fuel consumption of an engine is usually expressed in
A. kJ per kg
B. kW per kg
C. litres per hour only
D. kg per kWh
View answer and explanation
Correct Option: D
It is the mass of fuel used per unit of power per hour. A lower value means better fuel economy.
Q115Mechanical Engineering (SSC JE)
Medium
Knocking in a compression ignition engine is mainly caused by
A. a long ignition delay that lets a large quantity of fuel accumulate before ignition
B. self-ignition of the end gas
C. a lean air-fuel mixture
D. low compression ratio only
View answer and explanation
Correct Option: A
A long delay lets much fuel burn in a sudden uncontrolled phase. In SI engines, knock is auto-ignition of the end gas.
Q116Mechanical Engineering (SSC JE)
Easy
Supercharging an engine increases its power output mainly by
A. increasing the density of the air entering the cylinder
B. cooling the cylinder walls
C. reducing the compression ratio
D. reducing the speed of the engine
View answer and explanation
Correct Option: A
More air by mass allows more fuel to be burnt in the same swept volume.
Q117Mechanical Engineering (SSC JE)
Hard
In a vapour compression cycle, the enthalpies at the evaporator exit, compressor exit and condenser exit are 400, 450 and 250 kJ/kg respectively. The COP is
Water enters a cooling tower at 40 °C and leaves at 32 °C. The ambient wet bulb temperature is 28 °C. The approach of the tower is
A. 8 °C
B. 4 °C
C. 28 °C
D. 12 °C
View answer and explanation
Correct Option: B
Approach = cold water temperature − wet bulb temperature = 32 − 28 = 4 °C. The range is 8 °C.
Q121Mechanical Engineering (SSC JE)
Easy
Which of the following refrigerants has zero ozone depletion potential?
A. R-12
B. R-22
C. R-134a
D. R-11
View answer and explanation
Correct Option: C
R-134a contains no chlorine. R-12 and R-11 are CFCs and R-22 is an HCFC, all of which harm the ozone layer.
Q122Mechanical Engineering (SSC JE)
Easy
In a domestic refrigerator, the expansion device is usually
A. a float valve
B. a turbine
C. a thermostatic expansion valve
D. a capillary tube
View answer and explanation
Correct Option: D
A long narrow tube drops the pressure of the refrigerant by friction. It has no moving parts and suits small hermetic units.
Q123Mechanical Engineering (SSC JE)
Hard
In a Rankine cycle, the turbine work is 900 kJ/kg, the pump work is 20 kJ/kg and the heat added is 2200 kJ/kg. The cycle efficiency is
A. 36 percent
B. 40.9 percent
C. 44 percent
D. 40 percent
View answer and explanation
Correct Option: D
η = (900 − 20) / 2200 = 880/2200 = 0.40.
Q124Mechanical Engineering (SSC JE)
Hard
A boiler produces 8 kg of steam per kg of coal. The heat added per kg of steam is 2400 kJ and the calorific value of coal is 30 000 kJ/kg. The boiler efficiency is
A. 80 percent
B. 72 percent
C. 64 percent
D. 37.5 percent
View answer and explanation
Correct Option: C
η = (8 × 2400)/30 000 = 19 200/30 000 = 0.64.
Q125Mechanical Engineering (SSC JE)
Hard
The critical pressure ratio for the flow of superheated steam through a nozzle is about
A. 0.577
B. 0.9
C. 0.546
D. 0.528
View answer and explanation
Correct Option: C
It is (2/(n+1))^(n/(n−1)) with n = 1.3, giving 0.546. For dry saturated steam (n = 1.135) it is 0.577 and for air it is 0.528.
Q126Mechanical Engineering (SSC JE)
Easy
The degree of reaction of a Parsons turbine is
A. 100 percent
B. 0 percent
C. 25 percent
D. 50 percent
View answer and explanation
Correct Option: D
The fixed and moving blades are identical, so the pressure drop is shared equally.
Q127Mechanical Engineering (SSC JE)
Easy
A power plant has an average load of 40 MW and a peak load of 80 MW. The load factor is
Which of the following is a thermosetting plastic?
A. PVC
B. Nylon
C. Bakelite
D. Polythene
View answer and explanation
Correct Option: C
Thermosets cure with heat into a rigid cross-linked network and cannot be remelted. Nylon, PVC and polythene are thermoplastics.
Q149Mechanical Engineering (SSC JE)
Easy
Slip gauges are used
A. to measure surface roughness
B. to measure angles only
C. for checking the hardness of a part
D. as standards of length for calibration and precision setting
View answer and explanation
Correct Option: D
They are rectangular steel or ceramic blocks of accurately known thickness that can be wrung together to build a required length.
Q150Mechanical Engineering (SSC JE)
Easy
In statistical quality control, a p-chart is used to monitor
A. the range of a measured dimension
B. the number of defects per unit
C. the fraction of defective items in a sample
D. the mean of a measured dimension
View answer and explanation
Correct Option: C
It is an attribute chart. X-bar and R charts are used for measurable (variable) characteristics.
Questions about this paper
What is the RRB JE (Junior Engineer) 2026 question paper on this page?
It is an archived RRB JE (Junior Engineer) 2026 paper with 150 questions, kept for practice. Where a source is credited on the page, the paper comes from that source.
Which subjects does RRB JE CBT 2 Mechanical Engineering Practice Paper 02 (Exam Pattern, Solved Set) cover?
The 150 questions are grouped by subject: Mechanical Engineering (SSC JE) (100), General Science (25), General Awareness (15) and Computer Knowledge (10).
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