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# UPRVUNL’21 ME: Daily Practices Quiz. 22-Aug-2021

Quiz: Mechanical Engineering
Exam: UPRVUNL
Topic: Miscellaneous

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 8 Minutes

Q1. A fluid behave as an ideal gas when its pressure and temperature are respectively
(a) High and High
(b) Moderate and High
(c) Low and Low
(d) Low and High

Q2. The lengths of the links of a simple 4-bar mechanism with only revolute pairs are p, q, r and s units. Given that p<q<r<s. Which of these links should be the fixed so that resultant mechanism would be a ‘double crank’ mechanism?

Q3. According to Kennedy’s theorem, the instantaneous centres of three bodies having relative motion lie on a
(a) Curved path
(b) Straight line
(c) Point
(d) Approximate straight line

Q4. What is the pressure difference between inside and outside a droplet of water?
(a) 2σ/d
(b) 4σ/d
(c) 8σ/d
(d) 12σ/d

Q5. Weber number is defined as the ratio of inertia force to
(a) Viscous force
(b) Elastic force
(c) Surface tension force
(d) Gravity force

Q6. What is an azeotrope?
(a) A halogen refrigerant
(b) A refrigerant dissolved in alcohol
(c) A mixture of refrigerants without phase separation
(d) Mixture of two crystal structure

Solutions
S1. Ans. (d)
Sol. A fluid behaves as perfect gas or ideal gas at low pressure and high temperature.
S2. Ans (a)
Sol.

For Class- I
If the shortest link (s) is fixed, then we obtain a double crank Mechanism.
If link opposite to the shortest link (s) is fixed then we obtain double rocker Mechanism
If a link other than the shortest or opposite to the shortest link is fixed, then we obtain a crank- rocker Mechanism.
For class-II
By fixing any link, we obtain double rocker Mechanism.

S3. Ans (b)
Sol. Kennedy’s theorem states that when three links are in relative motion, then the I – centre of the three links will lie on the same line.

S4. Ans (b)
Sol. Pressure difference between inside and outside a droplet of water = 4σ/d
∵ Bursting force = p×πd²/4
Resisting force = σ ×π d
Bursting force= Resisting force
p×πd²/4=σ×πd
or p=4σ/d
S5. Ans.(c)
Sol.
Weber number:
W=((Inertia force)/(Surface tension))^(1/2)=V/√(σ/ρL)
Mach number:
M=((Inertia force)/(Elastic force))=V/√(K/ρ)
Euler’s number:
E=((Inertia force)/(Pressure force))^(1/2)=V/√(p/ρ)

S6. Ans.(c)
Sol. Azeotrope is a mixture of refrigerants without phase separation.

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