Mechanical Engineering Answers

Air initially at 75 psia and 65 0F is compressed to a final pressure of 300 psia and temperature of 320 0F. Find the polytropic exponent for the process

A steel rod subjected to compression is modeled by two bar elements as shown in figure 1. Determine the nodal displacement and the axial stress in each element. What other concerns should be examined?


0.5 m


E = 207 GPa


0.5 m


A = 500 mm


12KN


Figure(1)

An aircraft weighting 156960 N is powered by a jet engine whose thrust is independent of flight speed. The maximum rate of climb at sea level occurs at 152.5 m/s. The wing area is 46 m2. The drag polar is given by

During the constant volume reversible non-flow process with air, the temperature drops from 400K to 320K. Show process on the p-V and T-s coordinates and find the heat transfer in kJ/kg.

During the constant pressure reversible non-flow process with air, the temperature increases from 400 0F to 1600 0F. Show process on the p-V and T-s coordinates and find the heat transfer in BTU/lbm.

Four pounds of certain gas receive 50 BTU of heat during a constant temperature reversible non-flow process at 165 0F. Find a.) the change of specific entropy, BTU/lbm.0R, and b.) the work done, BTU. Show the process on the p-V and T-s diagram.

During the unidentified process with air, the temperature decreases from 600 0F to 200 0F. Find a. ) the change of internal energy, b.) the change of enthalpy.

Air initially at 100 0F and 100 psia and occupying a volume of 0.5 ft3 undergoes a reversible non-flow constant temperature process such that the final pressure becomes 20 psia. find the work done, ft.lbf.

Air initially at 15 psia and 60 0F is brought to a final temperature of 200 0F by a reversible non-flow process. Correlate with problem 7, show the processes on the p-V and T-s diagram and find the heat transferred in BTU/lb if a.) n=0, b.)n=∞, c.) n=k and n=1.2.

Air initially at 50 psia and 140 0F undergoes a polytropic process such that the temperature becomes 40 0F. The polytropic exponent for the process is equal to 1.3. Find the final pressure and specific volume.