Question

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

Answer 1

6 km/h is the answer by shortest method

Answer 2

Answer:

The velocity of river is 6 km/h.

Explanation:

Given that,

Velocity of boat = 8 km/h

Resultant velocity = 10 km/h

Let  $v_{rb}$ is the resultant velocity of boat with river.

The resultant velocity of boat with river is

$v_{rb}= \sqrt{v_{r}^2+v_{b}^2}$

$(v_{rb})^2=(v_{r})^2+(v_{b})^2$

$(v_{r})^2=(v_{rb})^2-(v_{b})^2$....(I)

Where, $v_{rb}$ = resultant velocity of boat with river

$v_{r}$= velocity of river

$v_{b}$ = velocity of boat

Put the value of $v_{b}$ and $v_{rb}$ in equation (I)

$(v_{r})^2=(10)^2-(8)^2$

$v_{r}=6\ km/hr$

Hence, The velocity of river is 6 km/h.