Basic Mechanical Engg. - May 2014
First Year Engineering (Set B) (Semester 1)
TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Explain the difference between malleability and ductility(2 marks) 1 (b) Explain the stress-strain diagram for mild steel. (2 marks) 1 (c) Give the classification of carbon steel. (3 marks)
Answer any one question form Q1.(d) & Q1.(e)
1 (d) Explain the Steel and Iron Carbon diagram.(7 marks) 1 (e) A rod 150 cm long and diameter 2 cm is subjected to an axial pull of 20 kN. If the modulus of elasticity of the material of the rod is 2 × 105 N/mm2 determine stress, strain, and the elongation of the rod.(7 marks) 2 (a) Briefly explain the devices used for measuring the pressure of a fluid.(2 marks) 2 (b) Explain the principle of temperature measurement.(2 marks) 2 (c) Describe vernier caliper with neat sketch.(3 marks)
Answer any one question from Q2.(d) & Q2.(e)
2 (d) Explain the construction and working principle of a simple lathe machine.(7 marks) 2 (e) Explain the principle of venturimeter with a neat sketch and derive the expression for the rate of flow of fluid through it.(7 marks) 3 (a) What do you mean by vacuum pressure.(2 marks) 3 (b) State the Newton's law of viscosity and give examples of its application.(2 marks) 3 (c) What factors decide whether Kaplan, Francis or a Pelton type turbine would be used in a hydroelectric project? (3 marks)
Answer any one question from Q3.(a) & Q3.(e)
3 (d) State Bernoulli's theorem and derive equation for the flow of an incompressible fluid. Mention the assumptions made for deriving it.(7 marks) 3 (e) Calculate specific weight, density, specific volume and specific gravity of petrol, if one liter of petrol weighs 6.867 N.(7 marks) 4 (a) State and explain second law of thermodynamics. (2 marks) 4 (b) Show the various process of steam in a T-S diagram. (2 marks) 4 (c) How boilers are classified? Write down few names of mountings and accessories of a boiler.(3 marks)
Answer any one question from Q4.(d) & 4.(e)
4 (d) Calculate the internal energy of 1 kg of steam at a pressure of 10 bar, when the steam is
(i) 0.9 dry (ii) dry saturated (iii) super heated to 250 °C(7 marks) 4 (e) The following observations were made in a boiler
|Coal used = 200 kg/hr||Mass of steam = 2000 kg/hr|
|Steam pressure = 11.2 bar||Dryness fraction = 0.95|
|Feed water temperature = 32.15 °C||Calorific value of coal = 28800 kj/kg|
Calculate the equivalent evaporation from and at 100 °C per kg of coal and boiler efficiency.(7 marks) 5 (a) What is Carnot cycle and its importance?(2 marks) 5 (b) Write any four advantage of 4 stroke petrol engine over 2 stroke petrol engine.(2 marks) 5 (c) For the same compression ratio and heat supplied, state the order of decreasing air standard efficiency of Otto, diesel and dual cycle. (3 marks)
Answer any one question from Q5.(d) & Q5.(e)
5 (d) Find the power output of a diesel engine working on a diesel cycle with compression ratio of 16 and air flow rate of 0.25 kg/sec. the initial condition of air at 1 bar absolute and 27 °C temperature, heat added per cycle 2500 kJ/kg.(7 marks) 5 (e) The minimum pressure and temperature in a Otto cycle are 100 kPa and 27 °C. The amount of heat added to the air per cycle is 1500 kJ/kg. Determine the pressures and temperatures at all points of the air standard Otto cycle. Also calculate the specific work and thermal efficiency of the cycle for compression ratio of 8 : 1.(7 marks)