Lake tuscaloosa has an elevation of 223'. it was created in 1970 by damming north river, which feeds into the black warrior river at an elevation of 123'. if the average flow rate through north river is 3 m3 /s, and 90% of the river is diverted to a hydroelectric facility with an efficiency of 91%, find the electricity that could be generated here, in kwh, per year of op

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

Aturntable a is built into a stage for use in a theatrical production. it is observed during a rehearsal that a trunk b starts to slide on the turntable 10 s after the turntable begins to rotate. knowing that the trunk undergoes a constant tangential acceleration of 0.31 m/s2, determine the coefficient of static friction between the trunk and the turntable.

A51 kg woman skis down a hill and her kinetic energy is 9.96e4 j. what is her speed?