The diameters of the main rotor and tail rotor of a single-engine helicopter are 7.65 m and 1.05 m, respectively. the respective rotational speeds are 454 rev/min and 4,130 rev/min. calculate the speeds of the tips of both rotors. compare these speeds with the speed of sound, 343 m/s.

An ascending elevator, hanging from a cable, is coming to a stop. part a part complete identify all forces acting on the elevator from the list below. select all that apply. select all that apply. kinetic friction normal force tension weight static friction submitprevious answers correct part b draw a free-body diagram of the object. draw the vectors starting at the black dot. the location and orientation of the vectors will be graded. the exact length of your vectors will not be graded but the relative length of one to the other will be graded.

An electric power distributor charges residential customers $0.10 per kilowatt-hour (kwh). the company advertises that "green power" is available in 150 kwh blocks for an additional $4 per month. (green power is generated from solar, wind power, and methane sources.) if a certain customer uses an average of 391 kwh per month and commits to one monthly 150 kwh block of green power, what is her annual power bill

Along wire of diameter 1 mm is submerged in an oil bath of temperature ∞ 31°c. the wire has an electrical resistance per unit length of 0.01 ω/m. if a current of 103 a flows through the wire and the convection coefficient is 500 w/m2·k, what is the steady-state temperature of the wire? from the time the current is applied, how long does it take for the wire to reach a temperature that is within 1°c of the steady-state value? the properties of the wire are 8000 kg/m3, 500 j/kg·k, and 20 w/m·k.