Question

A Chinook salmon has a maximum underwater speed of 3.0 m/s, and can jump out of the water vertically with a speed of 5.3 m/s. A record salmon has a length of 1.5 m and a mass of 55 kg. When swimming upward at constant speed, and neglecting buoyancy, the fish experiences three forces: an upward force F exerted by the tail fin, the downward drag force of the water, and the downward force of gravity. As the fish leaves the surface of the water, however, it experiences a net upward force causing it to accelerate from 3.0 m/s to 5.3 m/s. Assuming the drag force disappears as soon as the head of the fish breaks the surface and that F is exerted until two-thirds of the fish's length has left the water, determine the magnitude of F.

Answer 1