3. you are to determine the power rating of the motor in an elevator system. the elevator (with a full load) weights 1700 kg and is required to move upward 3 m/sec at constant speed. the lifting mechanism is 90% efficient (i. e., 10% of the power generated by the motor is wasted in the mechanism, e. g., for overcoming friction). what is the minimum output power rating in hp of the motor that meets the requirement?

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.