Mechanical Engineering - Online Test
Q1. A thin cylinder of inner radius 500mm and thickness 10mm is subjected to an
internal pressure of 5MPa. The average circumferential (hoop) stress in MPa is
Answer : Option B
Explaination / Solution:
Given Data: p = 5MPa; d = 1000mm; t = 10mm
Hoop stress = pd/2t = 250MPa
Q2. A pump handling a liquid raises its pressure from 1 bar to 30 bar. Take the
density of the liquid as 990 kg /m3. The isentropic specific work done by the
pump in kJ/kg is
Answer : Option D
Explaination / Solution:
Work done by the pump = 
Q3. Which one of the following statements is TRUE for the ultrasonic machining (USM) process?
Answer : Option D
Explaination / Solution:
No Explaination.
Q4. Consider the differential equation 
Which of the following is a solution
to this differential equation for x > 0?
Which of the following is a solution
to this differential equation for x > 0?
Answer : Option C
Explaination / Solution:
Q5. A torque T is applied at the free end of a stepped rod of circular cross-sections as
shown in the figure. The shear modulus of the material of the rod is G. The
expression for d to produce an angular twist θ at the free end is 
Answer : Option B
Explaination / Solution:
Angular twist at the free end
Q6. A spherical steel ball of 12mm diameter is initially at 1000K. It is slowly cooled in
a surrounding of 300K. The heat transfer coefficient between the steel ball and
the surrounding is 5W /m2 K . The thermal conductivity of steel is 20W /mK . The
temperature difference between the centre and the surface of the steel ball is
Answer : Option D
Explaination / Solution:
Bi = hL/K = 5 ×0.002/20 = 0.0005
For the given condition the Biot number tends to zero, that means conduction
resistance is far less than convection resistance. Therefore temperature between
the centre and surface is very small.
Q7. It is desired to make a product having T-shaped cross-section from a rectangular aluminium
block. Which one of the following processes is expected to provide the highest strength of the
product?
Answer : Option C
Explaination / Solution:
No Explaination.
Q8. The state transition matrix for the system
is
is
Answer : Option C
Explaination / Solution:
Q9. Two identical ball bearings P and Q are operating at loads 30kN and 45kN
respectively. The ratio of the life of bearing P to the life of bearing Q is
Answer : Option B
Explaination / Solution:
Q10. An ideal Brayton cycle, operating between the pressure limits of 1 bar and 6 bar,
has minimum and maximum temperatures of 300K and 1500K. The ratio of
specific heats of the working fluid is 1.4. The approximate final temperatures in
Kelvin at the end of the compression and expansion processes are respectively
Answer : Option A
Explaination / Solution:
Ideal Brayton cycle
At the end of compression, temperature.
