Question

A boat is rowed across the river at the rate of 4.5km/hr. The river flows at the rate of 6km/hr. The velocity of boat in m/s is

1)2.9

2)3.1

3)2.1

4)5

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=4.5 km/hr
V_R = Velocity of river=6 km/hr

Apply pythagoras theoram,

Resultant velocity boat² = V_B² + V_R²
resultant velocity boat=
=
= 2.083 m/s