UPPSC Lec'21 ME: Daily Practices Quiz. 02-Nov-2021

Quiz: Mechanical Engineering
Exam: UPPSC AE/Lecturer
Topic: Miscellaneous

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

Q1. Material handling is considered as
(a) Economically waste it should be eliminated
(b) Economically waste but cannot be eliminated
(c) Economically profitable so should be increased
(d) It does not cost in any way

Q2. Which of the following drives is having the maximum power?
(a) DC motor
(b) Stepper motor
(c) Hydraulic drive
(d) Pneumatic drive

Q3. An open cycle constant pressure gas turbine uses a fuel of calorific value 40,000 kJ/kg, with air fuel ratio of 80: 1 and develops a net output of 80kJ/kg of air. The thermal efficiency of the cycle is
(a) 61%
(b) 16%
(c) 18%
(d) None of these

Q4. What is the unit of dynamic viscosity of a fluid termed ‘poise’ equivalent to?
(a) dyne/cm²
(b) gm-s/cm²
(c) dyne-s/cm²
(d) gm-cm/s

Q5. If the surface tension of water-air interface is 0.073 N/m, the gauge pressure inside a rain drop of 1 mm diameter will be
(a) 0.146 N/m²
(b) 73 N/m²
(c) 146 N/m²
(d) 292 N/m²

Q6. The pressure difference of two very light gases in two rigid vessels is being measured by a vertical U-tube water filed manometer. The reading is found to be 10 cm. What is the pressure difference?
(a) 9.81kPa
(b) 0.0981 bar
(c) 98.1 Pa
(d) 981 N/m²

Solutions

S1. Ans. (b)
Sol. Material handling is considered as Economically waste but cannot be eliminated.

S2. Ans. (c)
Sol. Hydraulic drives is having the maximum power.

S3. Ans (b)
Sol.
η =W_out/Q_in =(80×(m_a ) ̇)/(m_f×40000) ̇
Since m ̇_a/m ̇_f =80
η =(80×80)/40000×100=16%

S4. Ans (c)
Sol. Poise is a C.G.S unit of dynamic viscosity equivalent ot dyne s/cm²
1 poise = 1 dyne s/cm² = 10^(-5+4) NS/m² = 10^(-1) Ns/m² = 0.1 NS/m²

S5. Ans (d)
Sol. Pressure intensity inside a droplet
p=4σ/d=(4×0.073)/10^(-3) N/m^2=292 N/m²

S6. Ans (d)
Sol. (p_1-p_2)/ρg=0.1
(p_1-p_2 )=0.1×1000×9.81=981 N/m²