Mechanical Engineering - Online Test
Q1. For a floating body, buoyant force acts at the
Answer : Option D
Explaination / Solution:
Buoyancy force is the force due to displaced volume of water. Hence,
buoyancy force always act on the centroid of displaced volume.
Q2. In electrodischarge machining (EDM), if the thermal conductivity of tool is high
and the specific heat of work piece is low, then the tool wear rate and material
removal rate are expected to be respectively
Answer : Option A
Explaination / Solution:
No Explaination.
Q3. The solution of the differential equation, for 
with initial conditions y(0) = 0 and 
is (u(t) denotes the unit step function),
with initial conditions y(0) = 0 and is (u(t) denotes the unit step function),
Answer : Option A
Explaination / Solution:
Q4. The cross sections of two hollow bars made of the same material are
concentric circles as shown in the figure. It is given that r3> r1 and
r4> r2, and that the areas of the cross-sections are the same. J1 and J2 are the torsional rigidities of the bars on the left and right,
respectively. The ratio J2/J1 is
Answer : Option A
Explaination / Solution:
Torsional rigidity for any Shaft is given by,
J = GIP
Or J α IP (Polar moment of Inertia)
And for a hollow shaft,
Q5. A plastic sleeve of outer radius r0 = 1 mm covers a wire (radius
r = 0.5 mm) carrying electric current. Thermal conductivity of the
plastic is 0.15 W/m-k. The heat transfer coefficient on the outer
surface of the sleeve exposed to air is 25 W/m2-K. Due to the
addition of the plastic cover, the heat transfer from the wire to the
ambient will
Answer : Option A
Explaination / Solution:
r = 0.5 mm, r0 = 1 mm.
Given, the wire is like a cylinder. Hence, critical radius of insulation is
Now if we add insulation (plastic cover), the heat transfer will
increase.
Q6. In orthogonal turning of medium carbon steel, the specific machining energy
is 2.0 J/mm3. The cutting velocity, feed and depth of cut are 120 m/min,
0.2 mm/rev. and 2 mm respectively. The main cutting force in N is
Answer : Option D
Explaination / Solution:
No Explaination.
Q7. The value of the integral 
is equal to
is equal to
Answer : Option D
Explaination / Solution:
Q8. A cantilever beam having square cross-section of side a is subjected
to an end load. If a is increased by 19%, the tip deflection decreases
approximately by
Answer : Option D
Explaination / Solution:
From the deflection formula, for cantilever beam having point load at
its free end,
Hence, decrement in the deflection in percentage will be
Q9. The INCORRECT statement about regeneration in vapor power
cycle is that
Answer : Option C
Explaination / Solution:
No Explaination.
Q10. A direct current welding machine with a linear power source characteristic provides open circuit voltage of 80 V and short circuit current of 800 A. During welding with the machine, the measured arc current is 500 A corresponding to an arc length of 5.0 mm and the measured arc current is 460 A corresponding to an arc length of 7.0 mm. The linear voltage (E) arc length (L) characteristic of the welding arc can be given as (where E is in volt and L in in mm)
Answer : Option A
Explaination / Solution:
No Explaination.
