This is a timed quiz. You will be given 60 seconds per question. Are you ready?
The hydraulic radius of a sewer refers to the ratio of the cross-sectional area of flow to the wetted perimeter. (The wetted perimeter is the portion of a cross-section’s perimeter that is “wet.”) The equation that describes the hydraulic radius of a channel, Rh, is expressed as follows: Rh = A (cross sectional area of flow) / P (wetted perimeter)
The cut construction method for earth retaining system is described as when walls are constructed from the top down to the base (top-down construction), concurrent with excavation operations. Fill construction refers to a method used to construct a wall from the base to the top (bottom-up construction). The “cut” and “fill” designations refer to the manner by which the wall is constructed, not the nature of the earthwork performed during the construction process.
The composite C value for the given drainage area for a 10-year storm recurrence interval is 0.45. Solution: Calculate composite C by using the following equation: C = (C1A1 + C2A2 + C3A3) / (A1 + A2 + A3) C = [(0.25 acres x 0.49) + (0.25 acres x 0.22) + (0.10 acres x 0.95)]/ (0.25+0.25+0.10) C = 0.45
Euler’s Formula is used to determine the critical buckling load of a simply-supported column. Euler’s Formula is expressed as follows: Fcr = EIΠ2/L2 Where E = Young’s modulus of the material used to construct the column I = cross-sectional area moment of inertia L = column length
Answer: Copper The delocalized “sea of electrons” model describes bonding in metals. Therefore, the only metal, copper, must display this type of bonding.
For most proposed land development projects, pre- and post-development watershed drainage patterns are compared to determine if substantial hydrologic alterations will be made to the watershed’s groundwater recharge, water regime, and area runoff. The drainage patterns reviewed include the surface and subsurface paths of water entering, crossing, and leaving the site. Additionally, areas where water is stored within the project site are also evaluated for pre- and post-construction conditions.
AASHTO assumes that the height of a driver’s eye and the height of an object above pavement are 42 inches and 24 inches (respectively) when developing recommendations for minimum stopping sight distances. AASHTO’s recommended distances are a conservative estimate of how long it will take a driver to perceive a situation exists that will require them to stop, apply the brakes, and come to a complete stop. The stopping site distance is an important safety consideration to assure that drivers have a continuous length of visible roadway.
When evaluating the progress of a project using the Earned Value Management approach, a project is considered profitable when the actual budget spent is less than or equal to the earned value. A project is considered to be over budget whenthe actual cost is greater than the earned value. A project is considered to be behind schedule when the budgeted cost of work performed is less than the budgeted cost of work scheduled.
Footings are appropriate to use when foundation loads can be supported by shallow soils. Reinforced concrete footings are designed to handle the foundation loads and local soil characteristics. Deep foundations may be used when shallow soils are not able to support the foundation loads cost-effectively. Piles may be used when deep, competent soil or bedrock can be used to support the foundation loads.
When drinking treating water, the presence of a poor taste or unpleasant odor, or the awareness of an ambient water temperature may indicate that there is a water quality problem within a finished water storage facility. Stale water within a storage facility promotes the growth of microorganisms that cause poor tastes or unpleasant odors and is often a result of water stored too long. Stagnant water will approach ambient temperatures, and may be a result of short-circuiting or accumulated sediment that impedes mixing within a storage unit.
Cathodic protection is used to control corrosion. Corrosion is an electrochemical process in which an electrical current flows through a metallic substance, causing a chemical reaction that results in pitting and, ultimately, complete deterioration. Cathodic protection systems use the electrical properties of metallic substances to protect against the corrosion of metallic piping and structures by forcing an electrical interaction. There are two main types of cathodic protection systems: · Galvanic - uses a sacrificial anode, placed adjacent to the structure to be protected, that corrodes instead of the structure · Impressed current - a current is applied to a structure from an adjacent anode
The total volume of the grit chamber is 2,079 ft3 is required to handle an average flow of 3 million gallons per day (mgd), with a peak flow ratio of 2.5 with a detention time of 3 minutes. Solution: Volume of grit chamber = Peak Flow x detention time Where, peak flow = average flow x peak flow ratio = 3 mgd x 2.5 = 7.5 mgd Given, 1 mgd = 1.54 ft3/seconds (sec) Volume = 7.5 mgd x 1.54 ft3/sec x 3 minutes x 60 sec/minute = 2,079 ft3
Answer: Mg3(PO4)2 Phosphate is a polyatomic anion with the molecular formula PO43-, and magnesium typically takes an oxidation state of +2. The simplest way to balance these charges gives the correct molecular formula, Mg3(PO4)2.
The statement, “Sizing is based on the measured flow conditions” is not correct when considering the surface overflow rates of primary settling tanks. Typically, the primary settling tanks are sized based on the surface area calculations performed using 1) the design average flow conditions and 2) design peak hourly flow conditions. The larger surface area of the two is used to size the primary setting tank. Specific design requirements for primary settling tanks are set by state regulating agencies.
Answer: 5 hours In 15 hours, this substance has decayed to 1/8 of its original mass. In other words, the substance has progressed through three half-lives (1/2 x 1/2 x 1/2 = 1/8). Thus, a single-half life for this substance is 5 hours.
The basic types of connections for beams, columns, trusses, and joists are pin, roller, and fixed. Roller connections provide only vertical support while allowing for free horizontal movement and rotation. Pin connections provide vertical and horizontal support and allow rotation. Fixed connections provide vertical and horizontal support and limit rotation (moment).
Answer: Na+ Electrolytes conduct electricity in aqueous solution, and are typically found in the form of ions. In the context of the question, Na+ is the only electrolyte.
The Rankine and Coulomb Theories are used to analyze active and passive lateral earth pressure. The two theories are similar; however, the Rankine Theory assumes there is no adhesion or friction between the wall and the soil, and lateral pressure is limited to vertical walls. The Coulomb Theory assumes that there is friction between the wall and the soil and that lateral pressure is not limited to vertical walls.
Air-entrainment was a significant concrete technology advancement made in the 1930s to provide relief from internal pressure. Entrained air provides tiny areas within concrete into which water can expand when it freezes. Air-entrained concrete is recommended when a concrete structure is exposed to freezing conditions and is achieved by adding surfactants to a concrete mix.
Potential safety and/or operational issues associated with a bridge spanning a recently repaved roadway that now a vertical clearance of 4-inches less than posted includes all of the listed issues. Drivers of large vehicles depend on the posted clearance values to avoid collisions with the bridge structure. Collisions with overhead structures often lead to multiple crashes due to limitations on stopping site distances, design speeds, and traffic conditions. Traffic delays may result from overhead structure collisions, multiple vehicle crashes and repairs to the damaged structure.
