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1.
A 20º full depth involute spur pinion of 4mm module and 21 teeth is to transmit 15kW at 960rpm. Its face width is 25mm.
[1] The tangential force transmitted (in N) is [2 marks]
(A) 3552
(B) 2611
(C) 1776
(D) 1305[2] Given that the tooth geometry factor is 0.32 and the combined effect of dynamic load and allied factors intensifying the stress is 1.5; the minimum allowable stress (in MPa) for the gear material is [2 marks]
(A) 242.0
(B) 166.5
(C) 121.0
(D) 74.0asked in Mechanical Engineering, 2009
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2.
In a machining experiment, tool life was found to vary with the cutting speed in the following manner:
Cutting speed (m/min) Tool life (minutes) 60 81 90 36
[1] The exponent (n) and constant (k) of the Taylor’s tool life equation are [2 marks]
(A) n = 0.5 and k = 540
(B) n = 1 and k = 4860
(C) n = −1 and k = 0.74
(D) n = −0.5 and k = 1.155[2] What is the percentage increase in tool life when the cutting speed is halved? [2 marks]
(A) 50%
(B) 200%
(C) 300%
(D) 400%asked in Mechanical Engineering, 2009
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3.
Consider the following PERT network:
The optimistic time, most likely time and pessimistic time of all the activities are given in the table below :Activity Optimistic
time (days)Most likely
time (days)Pessimistic
time (days)1-2 1 2 3 1-3 5 6 7 1-4 3 5 7 2-5 5 7 9 3-5 2 4 6 5-6 4 5 6 4-7 4 6 8 6-7 2 3 4
[1] The critical path duration of the network (in days) is [2 marks]
(A) 11
(B) 14
(C) 17
(D) 18[2] The standard deviation of the critical path is [2 marks]
(A) 0.33
(B) 0.55
(C) 0.77
(D) 1.66asked in Mechanical Engineering, 2009
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4.
Radiative heat transfer is intended between the inner surfaces of two very large isothermal parallel metal plates. While the upper plate (designated as plate 1) is a black surface and is the warmer one being maintained at 727ºC, the lower plate (plate 2) is a diffuse and gray surface with an emissivity of 0.7 and is kept at 227ºC. Assume that the surfaces are sufficiently large to form a two-surface enclosure and steady state conditions to exist. Stefan Boltzmann constant is given as 5.67×10-8W/m2K4.
[1] The irradiation (in kW/m2) for the upper plate (plate 1) is [2 marks]
(A) 2.5
(B) 3.6
(C) 17.0
(D) 19.5[2] If plate 1 is also a diffuse and gray surface with an emissivity value of 0.8, the net radiation heat exchange (in kW/m2 ) between plate 1 and plate 2 is [2 marks]
(A) 17.0
(B) 19.0
(C) 23.0
(D) 31.7asked in Mechanical Engineering, 2009
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5.
The inlet and the outlet conditions of stream for an adiabatic steam turbine are as indicated in the notations are as usually followed
[1] If mass flow rate of steam through the turbine is 20kg/s, the power output of the turbine (in MW) is [2 marks]
(A) 12.157
(B) 12.941
(C) 168.001
(D) 168.785[2] Assume the above turbine to be part of a simple Rankine cycle. The density of water at the inlet to the pump is 1000kg/m3. Ignoring kinetic and potential energy effects, the specific work (in kJ/kg) supplied to the pump is [2 marks]
(A) 0.293
(B) 0.351
(C) 2.930
(D) 3.510asked in Mechanical Engineering, 2009
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6.
Match the items in Column I and Column II.
Column I Column II P. Metallic Chills 1. Support for the core Q. Metallic Chaplets 2. Reservoir of the molten metal R. Riser 3. Control cooling of critical sections S. Exothermic Padding 4. Progressive solidification
(A) P-1,Q-3,R-2,S-4
(B) P-1,Q-4,R-2,S-3
(C) P-3,Q-4,R-2,S-1
(D) P-4,Q-1,R-2,S-3
asked in Mechanical Engineering, 2009
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