You work for the city water department and need to pump 3400 liters/minute of water from a tank at ground level into a vented (i. e., open-top) water tower, 75 meters above ground. the pump can be considered adiabatic, and the combined efficiency of pump and its drive motor is 90 percent. determine: the electric power required (kw) to drive the pump if friction losses are neglected and the average velocity (m/s) of the water if a 20-cm diameter (id) pipe is used.

Antireflective coatings on solar cells are often made by applying a thin film of silicon nitride (sinx), which has an index of refractive of 1.2, on the top of the silicon solar cell, which has a refractive index of about 3.5. however, the sun emits radiation of various wavelengths which the solar cell absorbs, and the antireflective coating can only absolutely minimize the reflection of one of these wavelengths. the coating thickness is chosen to reduce the reflection of green/yellow light (e = 2.2 ev), which is the most intense color in the solar spectrum (shown below). which of the following coatings would minimize reflection of green/yellow light? the answer is 820 nm how? what is the angular width of the central maximum of an electron traveling at 2 x 108 m/s going through a single slit of width 1 mm.