Civil and Environmental Engineering Answers

A city discharges 100 (cum. Sec) m3/sec of sewage into a river, which is fully saturated with oxygen and flowing at the rate of 150 m3/sec during its lean days with a velocity of 0.1 m/sec. The 5th day BOD of sewage at the given temperature is 280 mg/L. Find when and where the critical DO deficit will occur in the downstream portion of the river and what is its amount. Assume f = 4.0 (Self-purification constant and KD = 0.1. *

A solid shaft 100 mm in diameter is subjected simultaneously to an axial compressive force of 50 kN and to a torque that twist through an angle of 1.5

A flat bar 75 mm wide by 9 mm thick and 1.2 m long is subjected to end moments of 202.5 N.m. Compute the deflection of the beam at the midspan if E = 200 000 MPa.

What is the ratio of the shear modulus G to the modulus of elasticity of steel if it has a Poisson’s ratio of 0.25.

A railroad track is laid at a temperature of 10

A wooden log is to be used as a foot bridge to span a gap. The log is required to support a concentrated load of 30 kN at midspan. Allowable shearing stress is 0.70 Mpa. Determine the diameter of the log that would be needed.

Compute the polar moment of inertia of a rectangular section with a base of 200 mm and a height of 300 mm.

Prove by solution that at the height of 55.86 meters of the Learning Tower of Pisa, Galileo's experiment is true for a 42g baseball and a 46g golf ball to hit the ground at the same time ; thus proving that acceleration due to gravity is constant.

A stone was release from a flying hot air balloon and hit the ground after 1.5 minutes. What was the height of the hot air balloon?( Neglect air resistance). What was the final velocity of the stone upon hitting the ground? ( Neglect air resistance). What is the stone's velocity after the 1 minute- fall? In another case, where air is blowing at a constant speed to the East of 100 m/s, what will the final velocity be, upon hitting the ground?