Civil Engineering Online Review

A jet 75 mmØ with a flow of 0.2 m³/sec. is inclined 30° with the horizontal. Determine the diameter of the jet at the maximum height.

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Pipes 1, 3 and 4 are connected in series and 2 and 3 are connected parallel to each other. If the discharge of pipeline 4 is 5 liters/sec, find the discharge at pipeline 2.

Pipe              Diameter           Lengths        Friction factor

2                     400 mm            4000 m.                0.020

3                     300 mm            2000 m.                0.020

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An extremely simplified water supply system is shown in the figure. What is the calculated discharge at point B if water in neither flowing to nor from the elevated storage tank.

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A pipeline having a diameter of 300mm consists of 60m. cast iron pipe with 3-90° medium radius bend, 2 gate valves and one swing butterfly valve. Compute the total head loss in the pipe line using the equivalent length with a velocity of 1m/sec. Assume f = 0.019. Refer to the given table:

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If K = 2.2 GPa is the bulk modulus of elasticity for water, what pressure is required to reduce a volume by 0.6 percent?

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Water flows in the triangular channel at a rate of 222 lites/sec. Find the depth of flow if the channel slope is 0.0008 and n = 0.016. The two sides of the channel is incline at an angle of 60° with the horizontal.

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A concrete spillway controls a reservoir having an area of 46000 sq.m. with a permanent crest elevation of 64m. and a length of crest of 38.9 ft. is drawn from elevation of the water surface after 0.70 hours. Use Francis Formula.

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For optimum dimension, determine the width of the rectangular channel with slope S = 0.0008 and n = 0.012 if the rate of flow is 4 m³/s.

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Water is flowing at the rate of 230 liters per second in a 300 mm 90° elbow with a pressure of 207 kPa. Find the resultant thrust in the bend and assume the pipe is lying horizontal. Use the most nearest value.

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A water tank is filled with water to a height of 3.2 m. above the orifice which is connected at the side of the tank. If the orifice is 3.2m. above the ground find the time for the water to hit the ground.

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In the vertical side of the tank is an orifice having an area Aj. If the height of liquid above the orifice is H and W as the specific weight of the liquid, compute the force exerted on the jet.

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A rectangular tank is divided by a partition into two chambers as shown. An orifice having a cross sectional area of 0.2 m² for which C = 0.93 is located near the bottom of the chamber. At a certain time, the water level in chamber A is 305 cm. higher than in chamber B. Find the time it will take for the water surfaces in the two chambers to be at the same level. Use the most nearest value.

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An open channel having a trapezoidal section is required to discharge 200 m³/sec. of water when running full. If the slope S = 0.002 and n = 0.014, compute the bottom width for a most efficient section.

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The bottom width  of a canal is 4m. and the side slopes are 2 horizontal to 1 vertical. Find the hydraulic radius in meters when water flows 1.2m. deep.

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A rectangular tank of internal width 7m. partitioned as shown, contains oil and water. If the specific gravity of oil is 0.84, find its depth “h”. Use the most nearest value.

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A block of wood with a horizontal square section 12 inches x 12 inches has a depth of 9 inches. If is allowed to float on a body of liquid which consists of 7 inches layer of water above a 10 inches layer of mercury (sp.gr=13.6). If the specific weight of the block is 124 psf, determine the distance the bottom of the block will come to rest below the water-mercury interface. Use the most nearest value.

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In an undrained triaxial test on a sample of saturated clay the all around pressure is maintained at 1.0 tons/sq.ft. The unconfined compressive strength is 3.62 tons/sq.ft. At what vertical load in addition to the all-around pressure should the sample fail?

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In the deposit shown in the accompanying figure the groundwater level was originally at the ground surface. The water table was lowered by drainage to a depth of 20ft, where upon the degree of saturation of the sand above the lowered water table decreased to 20 percent. Compute the vertical effective pressure at the middle of the clay layer after lowering the water table.

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A shrinkage limit test on a clay soil gave the following data. (Hint: Assume that the total volume of the dry soil cake is equal to its total volume at the shrinkage limit)

Weight of shrinkage dish and saturated soil = 38.78 g

Weight of shrinkage dish and oven-dry soil cake = 30.46 g

Weight of shrinkage dish = 10.65 g

Weight of shrinkage dish = 16.29 cu.cm.

Total volume of oven dry soil cake = 10.00 cu.cm.

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A hand-carved sample of soft saturated clay has a volume of 100 cu.cm. and weighs 175g. If the oven-dry weight is found to be 120g. Compute the void ratio (e).

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A 50 cu.cm. sample of moist clay was obtained by pressing a sharpened hollow cylinder into the wall of a test pit. The extruded sample had an initial weight of 85g. and after oven-drying a weight of 60g. Assuming G_s = 2.70. Compute the degree of saturation (S_n).

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Which is not a soil characteristic that can be calculated from shrinkage limit?

a)  shrinkage ratio

b)  shrinkage limit

c)  volumetric change

d)  volumetric ratio

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Type of sewer which carry only liquid waste without fecal material.

a)  manhole

b)  clean out

c)  soil pipe

d)  waste pipe

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The shaking test (dilatancy) is used to separate.

a)  silt and clay

b)  sand and gravel

c)  clay and sand

d)  none of these

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Surface cooling of the earth that increase the temp. of altitude.

a)  Surface heating

b)  Temperature Inversion

c)  Inverter

d)  Global heating

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A 2.44m. wide rectangular channel conveys at 1.70 m³/s. The depth of water upstream is 2.13m. if the height of weir is 1.22m., using Francis formula, what is the weir length considering velocity of approach?

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A cylindrical tank having a diameter of 4m. is divided by a vertical partition placed upright at its mid-section, if the water surface on one side is 5m. higher than on the other side, how long will it be until the two surfaces are on the same level following a quick opening of a submerged square orifice 25mm x 25mm on the side of partition?

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A rectangular weir contracted a both ends is 10.27 m. wide extends across a rectangular channel. Find the head of water for a discharge of 3m³/sec.

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A dam 4m. on top 18 m. at the bottom and 25 m. high has water 20m. deep acting on its vertical sides. What is the stress at the heel. Wt. of concrete = 2200 kg/m³.

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A drainage canal having a trapezoidal shape has a base equal to 2m. and the depth of water is 1m. If the sides makes an angle of 45° with the horizontal, compute the hydraulic radius. S = 0.0015, n = 0.012.

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A block of wood with uniform horizontal section float in water with 20cm. projecting above the surface. The same block when placed in a body of oil (S = 0.80) floats with 18cm. projecting above the oil surface. Determine the sp.gr. of the wood.

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A vessel has an orifice located in the vertical side of a cylindrical vessel under a head “h”. The jet strikes a horizontal plane 2.5m. below the center of the orifice at a point 2.5m. measured horizontally from the vertical plane of the orifice. Determine the value of “h”.

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The figure shows the column loads and the footing elevation. The depth of the pad is adequate and the DL of the footing maybe neglected. The columns are axially loaded only. Determine the dimension of the footing if the allowable soil pressure is 2000 psf.

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A rectangular flume of most efficient proportion b = 2d has a perimeter of 6m. and carries a discharge of 2.70 m³/sec. If the same material were used for the most efficient trapezoidal section, determine the discharge of the new section.

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A pressure gauge at elevation 8 at the side of a tank containing a liquid reads 80 kPa. Another gauge at elevation 3 reads 120 kPa. Compute for the specific gravity of the liquid.

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