Mechanical Engineering - Online Test
Q1. A mass of 1kg is attached to two identical springs each with stiffness k = 20kN/m
as shown in the figure. Under frictionless condition, the natural frequency of the
system in Hz is close to
Answer : Option A
Explaination / Solution:
Natural frequency of the system
Q2. The temperature and pressure of air in a large reservoir are 400K and 3 bar
respectively. A converging–diverging nozzle of exit area 0.005m2 is fitted to the
wall of the reservoir as shown in the figure. The static pressure of air at the exit
section for isentropic flow through the nozzle is 50kPa. The characteristic gas
constant and the ratio of specific heats of air are 0.287kJ/kgK and 1.4
respectively
The density of air in kg/ m3 at the nozzle exit is
Answer : Option C
Explaination / Solution:
Given data:
T1 = 400k, P1 = 300 kPa, P2 = 50kPa, R = 0.289kJ / kgK
v = 1.4, A2 = 0.005m2
The happened process from entrance to exit is isentropic process, therefore
Q3. Under optimal conditions of the process the temperatures
experienced by a copper work piece infusion welding, brazing and
soldering are such that
Answer : Option D
Explaination / Solution:
Under the optimal conditions temperature of different processes
experienced by a copper work piece is given by
Twelding > Tbrazing > Tsoldering
Q4. Given f (z) = g(z) + h(z), where f, g, h are complex valued functions of a complex variable z. Which one of the following statements is TRUE?
Answer : Option B
Explaination / Solution:
g(z) and h(z) are differentiable then f(z) = g(z) + h(z) is differentiable.
Q5. The shear strength of a sheet metal is 300MPa. The blanking force required to
produce a blank of 100mm diameter from a 1.5 mm thick sheet is close to
Answer : Option C
Explaination / Solution:
Blanking force = τ . As = 300 × πdt = 300 × π × 100 × 1.5 = 141 kN
Q6. The temperature and pressure of air in a large reservoir are 400K and 3 bar respectively. A converging–diverging nozzle of exit area 0.005m2 is fitted to the wall of the reservoir as shown in the figure. The static pressure of air at the exit section for isentropic flow through the nozzle is 50kPa. The characteristic gas constant and the ratio of specific heats of air are 0.287kJ/kgK and 1.4 respectively
The mass flow rate of air through the nozzle in kg/s is
Answer : Option D
Explaination / Solution:
No Explaination.
Q7. The part of a gating system which regulates the rate of pouring
of molten metal is
Answer : Option C
Explaination / Solution:
Rate of poring molten metal is regulated by choke. As, the choke area
is the minimum area of the gating system, which decide the gating
will be pressurised and unpressurised (or turbulence will occur or
not). Hence, choke is the part which regulate the rate of pouring.
Q8. The Laplace transform of 
The Laplace transform of 
is
The Laplace transform of is
Answer : Option B
Explaination / Solution:
Q9. A disc of mass m is attached to a spring of stiffness k as shown in the figure. The
disc rolls without slipping on a horizontal surface. The natural frequency of
vibration of the system is 
Answer : Option C
Explaination / Solution:
No Explaination.
Q10. A mass m of a perfect gas at pressure p1 and volume V1 undergoes an isothermal process. The
final pressure is p2 and volume is V2. The work done on the system is considered positive. If R
is the gas constant and T is the temperature, then the work done in the process is
Answer : Option B
Explaination / Solution:
