Civil and Environmental Engineering Answers

A rectangular wooden beam (fb = 5.9 MPa, E = 17.3 GPa) has a cross-sectionalarea of 250 mm

by 500 mm. The length of the beam is 15 meters with pin and roller supports every fifth points. A vibrating

machine weighing 500 kg is located at the mid-lengthof the beam. The machine produces an

unbalanced force of 500 N operating at 300 rpm.Determine the following:

a) maximum static deformation under the weight of the machine,

b) maximum dynamic stress in the beam section under the unbalanced force,

c) force transmitted to the support, and

d) adequacy of the beam against bending. Use a dampingratio of 5%.

A firm is considering three mutually exclusive alternatives as part of a production improvement program.

The alternatives are:

A B C

Installed cost $10,000 $15,000 $20,000

Uniform annual benefit 1,625 1,530 1,890

Useful life, in years 10 20 20

The salvage value at the end of the useful life of each alternative is zero. At the end of 10 years,

Alternative A could be replaced with another A with identical cost and benefits. The maximum attractive

rate of return is 6%. Which alternative should be selected

An open cylindrical tank 4 ft in diameter and 6 ft deep is filled with water and rotated about its axis at 60 rpm. How much liquid is spilled, and how deep is the water at the axis? Ans. 15.3 ft , 3.55 ft , give the solution.

An open cylindrical tank 4 ft in diameter and 6 ft deep is filled with water and rotated about its axis at 60 rpm. How much liquid is spilled, and how deep is the water at the axis?

9.) The pressure head at A in pump A B is 120 ft when the energy change in the system (see Fig. 9-30) head through valve Z is 10 ft. Find all the flows and the elevation of reservoir Sketch the hydraulic grade lines.

10.) Solve the pipe network shown in the figure. The 12 in and 16in are of new cast iron, while the 18 and 24 in are of average concrete. Assume n=2.0 and use the values of f from figure 8.11 for complete turbulence. If the pressure at h is 80 psi, find the pressure at f.

5.) An old pipe, 600 mm I.D. and 1219m long, carries medium fuel oil at 30°C from A to B. The pressures at A and B are 393 kPa and 138 kPa respectively, and point B is 18.3 m above point A. Calculate the flow, using ∊ = 0.00049 m.

6.) A commercial solvent at 20°C flows from tank A to tank B through 152 m of new 150-mm asphalt-dipped cast iron pipe. The difference in elevation of the liquid levels is 7.0 m. The pipe projects into tank A, and two bends in the line cause a loss of 2 velocity heads. What flow will occur? Use ∊ = 0.00014 m.

7.) A 12-in-diameter new cast iron pipe is 1.0 mile long. Determine the discharge capacity of this pipe if the head loss is 24.5 ft using: a.) Hazen-Williams formula. b.) Manning formula.

1.) What size pipe will maintain a shear stress at the wall of 0.624 psf when water flows through 300 ft of pipe causing a lost head of 20.0 ft?

2.) Compute the critical velocity (lower) for a 100-mm pipe carrying water at 27°C.

3.) Water at 20°C flows in a 100-mm-diameter new cast iron pipe with a velocity of 5.0 m/s. Determine the pressure drop in kPa per 100 m of pipe and the power lost (in kilowatts) to friction.

4.) Water at 38°C flows from A to B through 244 m of average 300-mm-I.D. cast iron pipe (∊ = 0.00061 m). Point B is 9.1 m above A, and the pressure at B must be maintained at 138 kPa. If 0.222 m3/s is to flow through the pipe, what must be the pressure at A?

An open cylindrical tank 4 ft in diameter and 6 ft deep is filled with water and rotated about its axis at 60 rpm. How much liquid is spilled, and how deep is the water at the axis?

A reservoir supplies water to a horizontal 6′′ pipe 800 ft long. The pipe flows full and discharges into the atmosphere at the rate of 2.23 cfs. What is the pressure in psi midway in the pipe, assuming the only lost head is 6.20 ft in each 100 ft of length?

A 30 m steel tape was standardized at a temperature of 20°C and under a pull 5 kg. The tape was used in catenary at a temperature 25°C and under a pull of P kg. The cross-sectional area of the tape is 0.02 cm2, its weights per unit length is 22 g/m. Young’s modulus = 2 x 10-6 kg /cm2, α = 11 x 10-6 per °C. Find the correct horizontal distance, if P is equal to (i) 5 kg, and (ii) 11 kg.