A river flows due east at a speed of 3 m/s. She sits at the riverbed with a homemade bottle of

sangria, shouting at the stick-racing boats. A swimmer aims to swim due north across the river,

moving at 4 m/s relative to the water. The swimmer needs to make it to the other side, where she

waits with sangria and a Star Trek marathon.

Find:

The swimmer’s resultant speed relative to the riverbank.

The direction the swimmer actually moves.

How long it takes to cross a 100-meter-wide river.

Use vector addition:

V(resultant) = √(v_swimmer² + v_river²), because laughter, like physics, builds on itself.

To find the angle:

θ = arctan(v_river / v_swimmer), which in this case, equals the courage it takes to be truly seen.

The time to cross is based only on the swimmer’s speed perpendicular to the river’s flow. But the

world isn’t as predictable as these equations. Some currents are altered by those who move

through them.

And she did.