Quiz: Mechanical Engineering 01 June 2020

Quiz: Mechanical Engineering
Exam: UPSSSC JE
Topic: Miscellaneous

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

Q1. The Coriolis component of acceleration of a slider moving with velocity V on a link having angular velocity ω is
(a) Vω
(b) 2 Vω
(c) 2ω/V
(d) Vω/2

Q2. Weber number is defined as the ratio of
(a) inertia force to viscous force
(b) inertia force to gravity force
(c) inertia force to surface tension force
(d) inertia force to elastic force

Q3. The ratio of RMS value to the average value of an alternating current waveform is called
(a) Peak factor
(b) Power factor
(c) Form factor
(d) None of the above

Q4. Pyrometry deals with the measurement of
(a) Elevated temperature
(b) Shocks
(c) Humidity
(d) Current

Q5. Endurance limit is associated with
(a) Torsion
(b) Bending
(c) Shear
(d) Fatigue

Q6. Reynold’s number is the ratio of
(a) Thermal conductivity to kinematic viscosity
(b) Inertia force to viscous force
(c) Heat convected to heat conducted
(d) None of these

Q7. Efficiency of Carnot cycle is (Where,T1 and T2 are the highest temperature and lowest temperature during the cycle)
(a) T1/T2 -1
(b) 1-T2/T1
(c) T1/T2 +1
(d) T1/T2

Q8. When the Mach number is less than unity, then the flow is
(a) Supersonic
(b) Sonic
(c) Subsonic
(d) None of the above

Q9. The moment of inertia of a circular section of diameter D about its diameter is________the moment of inertia about the polar axis.
(a) four times
(b) double
(c) three times
(d) half

Q10. The heat that must be absorbed by ice of mass 500g at -10 Deg C to take it to water at 20 Deg C is (specific heat of ice is 2.2 kJ/kg-K, specific heat of the water is 4.2 kJ/kg-K and latent heat of fusion of ice is 300kJ/kg)
(a) 53 kJ
(b) 243 kJ
(c) 192 kJ
(d) 203 kJ

Solutions

S1. Ans (b)
Sol. The Coriollis component of acceleration is an acceleration of slider moving with velocity V, on a rotating link with angular velocity ω.
i.e. Coriollis component of acceleration =2ωV
It acts on the slider of quick-return motion mechanism.

S2. Ans (c)
Sol. Weber number is defined as the ratio of inertia force to surface tension force. Weber number is applicable for the applications where surface tension force dominates. E.g. Capillary action in a tube etc.

S3. Ans (c)
Sol. The ratio of RMS value to the average value of an alternating current waveform is called Form factor.
R.M.S. value of alternating current is 1/√2 times of maximum amplitude of alternating current and average value of alternating current is 2/π times of maximum amplitude of alternating current.

S4. Ans (a)
Sol. Pyrometry is the branch of science which deals with the measurement of elevated temperatures. Pyrometer is such a device which is used to measure higher temperature (from 300 Deg C to 6000 Deg C)

S5. Ans (d)
Sol. Endurance limit is defined as the maximum stress/load that a component can sustain without failure when it is being subjected to cyclic loading.

S6. Ans (b)
Sol. Reynold’ s Number(Re)=(Inertia Force)/(Viscous Force)=ρVd/μ
Here,
ρ=Density of fluid
V=Average velocity of fluid
d=Diameter of conduit
μ=Dynamic viscosity of fluid

S7. Ans (b)
Sol. Efficiency of Carnot cycle (η)=1-T2/T1

S8. Ans (c)
Sol.
1. If Mach Number (Ma<1) then flow is subsonic.
2. If Mach Number (Ma=1) then flow is sonic.
3. If Mach Number (Ma>1) then flow is supersonic.
4. If Mach Number (Ma>3) then flow is hypersonic.

S9. Ans (d)
Sol.
Moment of inertia about the diameter=(πD^4)/64
Moment of inertia about polar axis=(πD^4)/32

S10. Ans (d)
Sol. Heat absorbed by ice at -10 Deg C to convert into water 20 Deg C = heat taken by ice from -10 Deg C to 0 Deg C + heat taken for phase change of ice into water at 0 Deg C + heat taken by water from 0 Deg C to 20 Deg C
=0.5×2.2×(0-(-10)+0.5×300+0.5×4.2×(20-0)
=203 kJ

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