The council members of a small town have decided that an earth levee should be rebuilt and strengthen to protect against future flooding. the town engineer estimates that the cost of the work at the end of the first year will be $ 100,000. he estimates that in subsequent years the annual repair will decline by $ 15,000, making the second-year cost $ 85,000; the third-year $ 70,000 and so forth. the council members want to know what the equivalent present worth cost is for the first 5 years of repair work if the interest rate is 6%. the value is closest to?

If you were designing a bumper for a car, would you prefer it to exhibit elastic or plastic deformation? why? consider the functions of a bumper in both a minor "fender-bender" and a major collision.

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

For a gate width of 2 m into the paper, determine the force required to hold the gate abc at its location.