Design of Machine Elements - 2 - Mechanical Engineering (MCQ) questions and answers
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1) Determine the Sommerfeld number considering the following data for hydrodynamic bearing?
1. Diameter of bearing = 120 mm
2. Bearing pressure = 5 N/mm2
3. Oil viscosity = 30 cP
4. Journal speed = 900 rpm
5. Radial clearance = 150 microns
- Published on 19 Oct 15
a. 0.2360
b. 0.0144
c. 0.0115
d. 0.0178
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2) Which of the following formula is used to calculate oil-film thickness in hydrodynamic bearings?
- Published on 19 Oct 15
a. h = (c + Є cos θ)
b. h =(c – Є cos θ)
c. h = c (1+ Є sin θ)
d. h = c (1+ Є cos θ)
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3) Lubricating oil used in hydrodynamic bearing has total flow rate of 0.340 l/min and side leakage of 0.1520 l/min. If mass density of oil is 600 kg/m3 and specific heat is 1.05 kJ/kg oC, what is the rise in temperature if power lost in friction is 0.05 kW?
- Published on 19 Oct 15
a. 11.23o C
b. 15.11o C
c. 18.03o C
d. 22.23o C
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4) Lubricating oil of mass density 800 kg/m3 used in 360o hydrodynamic bearing has a flow rate of 6000 mm3. Neglecting side leakage if temperature rises to 10 oC and specific heat is 1.55 kJ/kg oC, what is the rate of heat dissipated in the bearing?
- Published on 19 Oct 15
a. 7.4 W
b. 236 W
c. 0.236 kW
d. 0.0744 kW
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5) A journal of 120 mm diameter rotates in a bearing at a speed of 1000 rpm. What is the power lost during friction if 8 kN radial load acts on the journal and coefficient of friction is 2.525 x 10-3?
- Published on 19 Oct 15
a. 0.126 kW
b. 0.253 KW
c. 2.365 kW
d. 7.615 kW
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6) What does number 6 indicate in the class of wire rope 6 x 37 (18/12/6/1)?
- Published on 19 Oct 15
a. Diameter
b. Strands
c. Wires
d. None of the above
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7) Lang lay ropes offer more resistance to __________
- Published on 19 Oct 15
a. fatigue failure
b. abrasive failure
c. both a. and b.
d. none of the above
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8) A V-belt pulley has belt velocity 20 m/s and mass 0.7 kg per meter. If allowable tension in the belt is 600 N then what will be the power transmitting capacity of belt?
(Assume μ = 0.5 & θ = 2.5 rad)
- Published on 19 Oct 15
a. 3.75 kW
b. 3.2 kW
c. 4.5 kW
d. 5.23 kW
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9) A V-belt pulley transmits power to flat belt pulley. If the coefficient of friction is 0.25 then which pulley governs the design? (β = 21o & α = 0.2)
- Published on 19 Oct 15
a. Flat pulley
b. V-belt pulley
c. Both a. and b.
d. None of the above
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10) Which of the following statements is/are true for V-belts?
- Published on 19 Oct 15
a. V-belt drives have low reduction ratio
b. Due to wedging action slip is negligible in V-belts
c. V-belt transmits power over long centre distances
d. All of the above
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Answer
Explanation
Related Ques
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ANSWER: Due to wedging action slip is negligible in V-belts
Explanation:
No explanation is available for this question!
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