Quiz: Mechanical Engineering

Exam: ISRO (TECHNICAL ASST.)

Topic: Miscellaneous

Each question carries 4 mark.

Negative marking: 1 mark

Time: 15 Minute

Q1. Iso-metric process is also called

(a) Isothermal process

(b) Isochoric process

(c) Isobaric process

(d) Adiabatic process

L1Difficulty 3

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Q2. Brayton Cycle consists of

(a) Two isochoric process and two isobars

(b) Two isothermal process and two isobars

(c) Two isochoric process and two isothermal process

(d) Two isobaric process and two isentropic process

L1Difficulty 3

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Q3. For stability of floating body

(a) Metacentre should be below Centre of gravity

(b) Metacentre should be above Centre of gravity

(c) Metacentre should be below centre of buoyancy

(d) None of these

L1Difficulty 3

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Q4. Nut and Screw thread form which type of pair?

(a) Lower pair

(b) Rolling pair

(c) Higher pair

(d) Cylindrical pair

L1Difficulty 3

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Q5. Force F in the given figure equals to

(a) √3 kN

(b) 2 kN

(c) – √3 kN

(d) 3√3 kN

L1Difficulty 3

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Q6. Tool wear is minimum in which of the following process?

(a) Electro-chemical machining

(b) Electric discharge machining

(c) Ultrasonic machining process

(d) Abrasive jet machining process

L1Difficulty 3

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Q7. Gun metal is an alloy of copper, tin and zinc. What is the percentage of copper in this alloy?

(a) 10%

(b) 4%

(c) 88%

(d) 15%

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Q8. Which of the following process is followed by expansion device of window AC?

(a) Isothermal process

(b) Isobaric process

(c) Isentropic process

(d) Isenthalpic process

L1Difficulty 3

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Q9. An object weighs 80 N in air and 30 N, when submerged in water then what is the weight of the water displaced by body?

(a)30 N

(b)60 N

(c)20 N

(d)50 N

L1Difficulty 3

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Q10. If a boat covers a 30 km in 10 min when it is running downstream and covers the same distance in 20 min when running upstream then find out the speed of flowing river water

(a) 37.5

(b) 12

(c) 12.5

(d) 50

L1Difficulty 3

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Solutions

S1. Ans (b)

Sol. Constant volume process is called isochoric process or iso-metric process.

S2. Ans (d)

Sol. Brayton Cycle is a gas power plant cycle in which there are four processes.

a-Isentropic compression

b-Constant pressure heat addition

c-Isentropic expansion

d- Constant pressure heat rejection

S3. Ans (b)

Sol. → Condition of equilibrium of floating and submerged bodies

Condition Submerged body Floating body

Stable B is above G M is above B and G

Unstable B is below G M is below G

Neutral B and G coincide M and G coincide

S4. Ans (a)

Sol. As Nut rotate as well as slide on the surface of the screw thread but both the motion are dependent on each other, so it is a lower pair.

S5. Ans.(a)

Fig.

Sol. from Lami’s theorem

1/sin150 = F/sin〖60°〗

F = sin〖60°〗/sin〖150°〗

F = √3 N

S6. Ans.(a)

Sol. Tool wear has following sequence in the different machining processes.

ECM<EDM<USM

S7. Ans.(c)

Sol. Gun metal has 88 copper ,8-10% tin and 2-4% zinc. It is mainly used for making gun.

S8. Ans.(d)

Sol. In window AC capillary tube is used as an expansion device and expansion in the capillary tube is throttling process which is an isenthalpic process.

S9. Ans.(d)

Sol. We know,

Weight of the water displaced=Buoyancy on body= (weight of body in air – weight of body in water)

=80-30

=50 N

S10. Ans (c)

Sol.

Let speed of river is v and speed of boat in still river is u and total distance covered either side is 30 km.

Given,

For Downstream flow-

30×1000/(u+v)=10×60

u+v=50……….(1)

For up-stream flow-

30×1000/(u-v)=20×60

u-v=25………..(2)

Solving equation (1) and (2)..

Speed of river (v)=12.5 m/s