Question

A Chinook (King) salmon (Genus Oncorynchus) can jump out of water with a speed of 6.75 m/s. If the salmon is in a stream with water speed equal to 1.65 m/s, how high in the air can the fish jump if it leaves the water traveling vertically upwards relative to the Earth?

Answer 1

The velocity of the salmon leaving the water in earth coordinates is the vector sum of 6.75 m/s (relative to water) and 1.65 m/s (relative to earth). The 6.75 m/s is a hypotenuse of a right triangle for which the upward velocity leg is
sqrt[(6.75)^2 - (1.65)^2] = 6.55 m/s

Set (1/2)M V^2 = M g H, with V = 6.55 m's, and solve for H.

The M's cancel.