A certain sea cow can paddle 2.0 m/s in still water. If she attempts to cross a river, from the south bank to the north with a current of 3.0 m/s flowing toward the east by paddling entirely perpendicularly to the flow of the river, in what direction will she be traveling relative to an observer on shore

v = 3.6m / s ,   θ = 56º

Explanation:

This is a relative speed exercise, let's use the Pythagorean theorem

        v = √ (v₁² + v₂²)

where v₁ is the speed of the sea still water and v₂ the speed of the current

let's calculate

       v = √ (2² + 3²)

        v = 3.6m / s

to find the direction we use trigonometry

      tan θ = v₂ / v₁

       θ = tan⁻¹ (v₂ / v₁)

let's calculate

       θ = tan⁻¹ (3/2)

        θ = 56º

this is poiselle's equation from fluid mechanic in physics. mech eng