# RGPV Basic Mechanical Engineering

# Previous year Question Paper April 2009

Note:- Attempt any five question .All questions carry equal marks.

**UNIT-I**

Q.1.Discuss composition,specific properties & main applications of the following materials:20

(a) Mild steel (Low carbon steel)

(a) Mild steel (Low carbon steel)

(b) High carbon steel

(c) High speed steel (d) Stainless steel.

**OR**

Q.2 Describe the mechanical properties of materials 20

(a) Tensile strength (tensile stress)

(b) Hardness

(c) Fatigue strength

(d) Modulus of elasticity

(e) Toughness

**UNIT-II**

Q.3 Explain the following properties of any measuring instruments: 20

(a) Hysteresis

(b) Sensitivity

(c) Response time

(d) Precision and accuracy

**OR**

Q.4 With the help of diagram explain various parts of a lathe machine & also enumerate various operations which can be performed on it. 20

**UNIT-III**

Q.5 What is Newton’s law of viscosity?

A plate requires 2 N force per unit area or 2 N/m² to move with a velocity of 60 cm/s over a fixed plate.The distance between two plates is 0.03 mm.Determine fluid viscosity between plates.5 + 15

**OR**

Q.6 Derive the Bernoulli’s equation from Euler’s equation for an ideal flow.

The water is flowing through a pipe having diameters 20 cm at inlet section 1 and 10 cm at outlet section 2. The rate of flow through pipe is 35 litres/s. The section 1 is 6 m above datum and section 2 is 4 m above datum. If pressure at section 1 is 39.24 N/cm², find the intensity of pressure at section 2. 6+14

**UNIT-IV**

Q.7 Explain the First Law of Thermodynamics with suitable examples. In a gas turbine the gas enters at the rate of 5 kg/s with a velcity of 50 m/s and enthalpy of 900 kJ/kg and leaves the turbine with a velocity of 150 m/s and enthalpy of 400 kJ/kg. The loss of heat from the gases to the surroundings is 25 kJ/kg. Assume for gas R = 0.285 kJ/kg-K and Cp = 1.004 kJ/kg-K and the inlet section conditions to be at 100 kPa and 27ºC. Determine the power output of the turbine and diameter of the inlet pipe 6+14

**OR**

Q.8 Give the two statements of Second Law of Thermodynamics. Which is the more effective way to increase the efficiency of a Carnot engine: To increase T1 keeping T2 constant or To decrease T2 keeping T1 constant. where T1 is the source temperature and T2 is the sink temperature.20

**UNIT-V**

Q.9 Show that the efficiency of the Otto cycle depends only on the compression ratio. In a SI engine working on the ideal Otto cycle,compression ratio is 5.5.The pressure and temperature at the beginning of compression are 1 bar and 27 ºC respectively. The peak pressure is 30 bar. Determine the pressure and temperatures at the salient points, the air-standard efficiency and the mean effective pressure. Assume ratio of specific heats to be 1.4 for air. 6 + 14

**OR**

Q.10 What is the basic difference between an Otto cycle and a Diesel cycle? Derive the expression for the efficiency and mean effective pressure of the diesel cycle 6 + 14