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1.
A cylinder is turned on a lathe with orthogonal machining principle. Spindle rotates at 200 rpm. The axial feed rate is 0.25 mm per revolution. Depth of cut is 0.4mm. The rake angle is 10°. In the analysis it is found that the shear angle is 27.75°.
[1] The thickness of the produced chip is [2 marks]
(a) 0.511 mm
(b) 0.528 mm
(c) 0.818 mm
(d) 0.846 mm[2] In the above problem, the coefficient of friction at the chip tool interface obtained using Earnest and Merchant theory is [2 marks]
(a) 0.18
(b) 0.36
(c) 0.71
(d) 0.908asked in Mechanical Engineering, 2003
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2.
A refrigerator based on ideal vapour compression cycle operates between the temperature limits of –20°C and 40°C. The refrigerant enters the condenser as saturated vapour and leaves as saturated liquid. The enthalpy and entropy values for saturated liquid and vapour at these temperatures are given in the table below.
[1] If refrigerant circulation rate is 0.025 kg/s, the refrigeration effect is equal to [2 marks]
(a) 2.1 kW
(b) 2.5 kW
(c) 3.0 kW
(d) 4.0 kW[2] The COP of the refrigerator is [2 marks]
(a) 2.0
(b) 2.33
(c) 5.0
(d) 6.0asked in Mechanical Engineering, 2003
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3.
Nitrogen gas (molecular weight 28) is enclosed in a cylinder by a piston, at the initial condition of 2 bar, 298 K and 1 m3. In a particular process, the gas slowly expands under isothermal condition, until the volume becomes 2m3. Heat exchange occurs with the atmosphere at 298 K during this process.
[1] The work interaction for the Nitrogen gas is [2 marks]
(a) 200 kJ
(b) 138.6 kJ
(c) 2 kJ
(d) -200 kJ[2] The entropy change for the Universe during the process in kJ/K is [2 marks]
(a) 0.4652
(b) 0.0067
(c) 0
(d) -0.6711asked in Mechanical Engineering, 2003
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4.
Heat is being transferred by convection from water at 48°C to a glass plate whose surface that is exposed to the water is at 40°C. The thermal conductivity of water is 0.6 W/mK and the thermal conductivity of glass is 1.2 W/mK. The spatial gradient of temperature in the water at the water-glass interface is dT/dy=1×104 K/m.
[1] The value of the temperature gradient in the glass at the water-glass interface is K/m is
[2 marks]
(a) -2 × 104
(b) 0.0
(c) 0.5 × 104
(d) 2 × 104[2] The heat transfer coefficient h in W/m2K is [2 marks]
(a) 0.0
(b) 4.8
(c) 6
(d) 750asked in Mechanical Engineering, 2003
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5.
A syringe with a frictionless plunger contains water and has at its end a 100 mm long needle of 1 mm diameter. The internal diameter of the syringe is 10 mm. Water density is 1000 kg/m3. The plunger is pushed in at 10 mm/s and the water comes out as a jet.
[1] Assuming ideal flow, the force F in Newton’s required on the plunger to push out the water is [2 marks]
(a) 0
(b) 0.04
(c) 0.13
(d) 1.15[2] Neglect losses in the cylinder and assume fully developed laminar viscous flow throughout the needle; the Darcy friction factor is 64/Re. Where Re is the Reynolds number. Given that the viscosity of water is 1.0 × 10-3 kg/sm, the force F in newtons required on the plunger is [2 marks]
(a) 0.13
(b) 0.16
(c) 0.3
(d) 4.4asked in Mechanical Engineering, 2003
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6.
A uniform rigid slenderbar of mass 10 kg, hinged at the left end is suspended with the help of spring and damper arrangement as shown in the figure where K = 2kN/m, C =500 Ns/m and the stiffness of the torsional spring Kθ is 1 kN/m/rad. Ignore the hinge dimensions.
[1] The un-damped natural frequency of oscillations of the bar about the hinge point is
[2 marks]
(a) 42.43 rad/s
(b) 30 rad/s
(c) 17.32 rad/s
(d) 14.14 rad/s[2] The damping coefficient in the vibration equation is given by [2 marks]
(a) 500 Nms/rad
(b) 500 N/(m/s)
(c) 80 Nms/rad
(d) 80 N/(m/s)[3] Z2 and Z4 are [2 marks]
(a) 64 and 45
(b) 45 and 64
(c) 48 and 60
(d) 60 and 48[4] The center distance in the second stage is [2 marks]
(a) 90 mm
(b) 120 mm
(c) 160 mm
(d) 240 mmasked in Mechanical Engineering, 2003
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