The Dolphin emits short bursts of ultrasound. The echoes of the ultrasound help the dolphins find fish. A SONAR receives a strong echo of ultrasonic signal it sent downwards into the sea 3.6 seconds after the transmission. Calculate the depth of the sea-bed if the speed of ultrasonic waves in sea-water is 1500 m/s.

Aplayground merry-go-round has a radius of 4.6 m and a moment of inertia of 200 kg-m2 and turns with negligible friction about a vertical axle through its center. a child applies a 26.0 n force tangentially to the edge of the merry-go-round for 15.0 seconds. if the merry-go-round is initially at rest, how much work did the child do on the merry-go-round?