Question

A boat is sent across a river with a velocity of 8 km per hour. if the resultant velocity of boat is 10 km per hour then calculate the velocity of the river.

Answer 1

The boat’s velocity and the river velocity will give the boat a new resultant velocity.
As the boat’s velocity is perpendicular to river velocity,

Assume that,
V_B = Velocity of boat
V_R = Velocity of river

Apply pythagoras theoram,

Resultant velocity² = V_B² + V_R²
10² = 8² + V_R²
100 = 64 + V_R²
V_R² = 36
V_R = 6 km/h