Quiz: Mechanical Engineering 4 May 2020

Quiz: Mechanical Engineering
Exam: UPSSSC JE
Topic: Miscellaneous

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

Q1. Mostly diamond riveted joint is preferred in ___________ joints.
(a) Butt
(b) Lap
(c) Double riveted lap joint
(d) All of the above

Q2. Ratio of longitudinal stress to hoop stress in thin cylinder is
(a) 1
(b) 2
(c) 0.5
(d) 0.25

Q3. If a composite bar of copper and aluminium is heated. The stresses developed in copper and aluminium will be
(a) Compressive and tensile
(b) Tensile and bending
(c) Shearing and bending
(d) Tensile and compressive

Q4. Damping capacity of a material is its ability to:
(a) absorb shocks
(b) absorb impacts
(c) withstand creep failure
(d) absorb vibrations

Q5. The radius of wire is stretched by a load is halved then its Young’s modulus will be
(a) Half
(b) Unaffected
(c) Double
(d) One fourth

Q6. The cam-follower should move with ___________ in high speed engines.
(a) S.H.M.
(b) Uniform velocity
(c) Cycloidal motion
(d) None of the above

Q7. Pitot tube is used for the measurement of
(a) Pressure
(b) Velocity
(c) Flow
(d) Discharge

Q8. In Carnot cycle heat is transferred at
(a) Constant pressure
(b) Constant volume
(c) Constant temperature
(d) Constant enthalpy

Q9. Supercharging is the process of-
(a) Supplying the intake of an engine with air at density higher than the density of the surrounding
(b) Providing forced cooling air
(c) Injecting excess fuel for raising more load
(d) Raising exhaust pressure

Q10. When torque is applied on any shaft, the value of shear stress is:
(a) uniform in cross section
(b) maximum at circumference
(c) minimum at circumference
(d) none of the above

Solutions

S1. Ans.(a)
Sol. Mostly diamond riveted joint is preferred in butt joints due to its strength and reliability. This is not possible with lap joint.

S2. Ans.(c)
Sol. We know that
Longitudinal stress=Pd/4t
Hoop stress=Pd/2t
Hence, Longitudinal stress= 0.5 × Hoop stress

S3. Ans.(d)
Sol. As thermal expansion coefficient of aluminium is more than that of copper. So, aluminium will try to pull copper piece in composite bar and in contradiction, copper piece will try to compress aluminium.
Hence, tensile stress will develop in copper and compressive stress will develop in aluminium.

S4. Ans.(d)
Sol. Damping capacity is defined as the ability of the material to absorb vibrations. It is measured mathematically as damping coefficient.

S5. Ans.(b)
Sol. As we know that Young’s modulus is the property of the material. So, it is not affected by any changes in the dimension.

S6. Ans.(c)
Sol. For high speed, we use cycloidal motion cam-follower. In other motion, wear and tear of cam-follower will increase at high speeds.

S7. Ans.(b)
Sol. Pitot tube is used for the measurement of velocity of flow in a pipe or conduit with the help of manometer. By measuring static and dynamic heads, flow velocity can be calculated.

S8. Ans.(c)
Sol. There are four processes in Carnot’s cycle, constant temperature heat addition, reversible adiabatic expansion, constant temperature heat rejection and reversible adiabatic compression.

S9. Ans.(a)
Sol. Supercharging is the process of supplying the intake of an engine with air at density higher than the density of the surrounding. Supercharging increases brake power in IC engines because brake power is a function of air density in IC engines. At high altitudes, supercharging is very useful because density of air in atmosphere decreases which causes engine brake power reduction.

S10. Ans.(b)
Sol. In case of pure shear or torque application on shaft, it is subjected to only shear which varies from center to circumference linearly.
Because, τ ∝ r
It is maximum at the circumference.

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