Mechanical Engineering Answers

A mixture of gases has the following composition by mass : N2 = 60 %, O2 = 30 % CO, = 10 %. 1 kg of mixture at 1 bar and 40°C is compressed to 5 bar. The index of compression may be taken as 1.2. Find the work done, heat transfer and change in entropy during the process. Also, find the molecular weight, gas constant and specific heat at constant pressure for the gas. Take Cp, for constituent gases as 1.04, 0.924 and 0.85 kJ/kgK for nitrogen, oxygen and carbon-dioxide respectively.

In an engine cylinder a gas has a volumetric analysis of 18% CO2, 12.5 % O2, and 74.5 % N2. The temperature at the beginning of expansion is 950°C and the gas mixture expands reversibly through a volume ratio of 8: 1, according to the law PV1.2 = C. Calculate per kg of gas (i) the work done (ii) the heat flow (iii) the change of entropy per kg of mixture. The values of Cp for the constituents CO2, O2, and N2 are 1.235 kJ/kgK, 1.088 kJ/kgK and 1.172 kJ/kgK respectively.

A 30 mm steel rod when subjected to an axial tensile force was subjected to a strain of 0.60X10-3 . find the tensile force that caused the above strain. Take E = 200 KN/mm2 

A l m rigid tank contains propane molecular weight 44) at 100 kPa, 300 K and connected by a valve to another tank of 0.5 m with propane at 250 kPa. 400 K. The valve is opened and the two tanks come to a uniform state at 325 K What is the final pressure?

The gas equation is PV = nRT. If P the pressure is 2.0 atm, V the volume of the gas is 6 m3, R the gas constant is 0.08206 m3 atm mole-1 K-1 and T is 300 degrees Kelvin, what are the units of n and what is its numerical value? 

Determine the moment of inertia of the closed area with respect to the x and y axis as shown in figure.

Analyze the beam shown in fig.1 using methods you have learned in this subject and compare the results of the analysis.

Odd roll numbered students:    X = 16' and Y = 24'

Even roll numbered students:   X = 18' and Y = 22'

Answer hints:

1.1 Introduction: (methods and assumptions)

1.2 Objectives:

1.3 By using the slope-deflection method

1.4 By using the moment distribution method

1.5 Compute maximum moment at Y/2. DL = 1k/ft, LL = 1 k/ft

1.6 Results and discussion

Analyze the beam shown in fig.1 using methods you have learned in this subject and compare the results of the analysis.

Odd roll numbered students:    X = 16' and Y = 24'

Even roll numbered students:   X = 18' and Y = 22'

Answer hints:

1.1 Introduction: (methods and assumptions)

1.2 Objectives:

1.3 By using the slope-deflection method

1.4 By using the moment distribution method

1.5 Compute maximum moment at Y/2. DL = 1k/ft, LL = 1 k/ft

1.6 Results and discussion

 15 mm dia SS (Young’s modulus = 200 Gpa) rod is coated with HA (Young’s modulus = 300 Gpa). What should be the coating thickness (in mm) so that the Young’s modulus of the composite is 209 Gpa (use mixture rule)?

8. Figure shown

represents a schematic

diagram of a Porter

governor. Each fly ball

weighs 16.1 lb and the

central weight D is 40 lb.

Determine the rotational

speed in rpm about the

vertical axis AD at which

the weight D begins to

rise.