Adolphin in seawater at a temperature of 25°c emits a sound wave directed toward the ocean floor 154 m below. how much time passes before it hears an echo? (the speed of sound in ocean water is 1533 m/s.)

Asmall object with mass 0.200 kg swings back and forth on the lower end of a light rope that is 3.00 m long. the upper end of the rope is attached to the ceiling. as the object swings through its lowest position, where the rope is vertical, the speed of the object is 5.80 m/s. at this point in the motion, what is the tension in the rope? (use g = 9.80 m/s2.)