A boat crosses a river of width 121 m in which the current has a uniform speed of 0.654 m/s. The pilot maintains a bearing (i. e., the direction in which the boat points) perpendicular to the river and a throttle setting to give a constant speed of 2.52 m/s relative to the water. What is the magnitude of the speed of the boat relative to a stationary shore observer

The frequency of a tuning fork can be found by the method shown. a long tube open at both ends is submerged in a beaker of water, and the vibrating tuning fork is placed near the top of the tube. the length l of the air column is adjusted by moving the tube vertically. the sound waves generated by the fork are reinforced when the length of the air column corresponds to one of the resonant frequencies of the tube. the smallest value for l for which a peak occurs in sound intensity is 7 cm. l what is the frequency of the tuning fork? the speed of sound in air is 345 m/s. answer in units of hz