Plateau Creek in Colorado carries 10 m3/s of water with a Selenium (Se) concentration of 0.003 mg/L. A farmer starts withdrawing 2 m3/s of the creek water to irrigate his land. During irrigation, the water picks up Se from the salts in the soil. One third of the irrigation water is lost to the ground and plants, and the other two-thirds is returned back to Plateau Creek. The irrigation run-off back to the creek contains 1.5 mg/L Se. Se is a conservative, non-reactive substance, and the stream does not pick up more Se from any other source. If the farmer irrigates continuously, what will be the steady-state concentration of Se in Plateau Creek, downstream from the farm (after the irrigation run-off returns to the Creek)

The force on a cutting tool are 2600n vertically downward and 2100 horizontal. determine the resultant force acting on the tool and the angle at which it acts.

An ideal otto cycle with air as the working fluid has a compression ratio of 8. the minimum and maximum temperatures in the cycle are 300 k and 1340 k. use constant specific heats at room temperature to determine (a) the amount of heat transferred to the air during the heat- addition kj/kg, (b) the thermal efficiency, and (c) the thermal efficiency of a carnot cycle ope limits. process, in rating between the same temperature

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?