Question

a boat is sent across a river with a velocity of 8 kilometre per hour if the resultant velocity of boat is 10 kilometre per hour then the velocity of the river is?​

Answer 1

Answer:

The velocity of river is 6 km/h.

Explanation:

Given that,

Velocity of boat = 8 km/h

Resultant velocity = 10 km/h

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

The resultant velocity of boat with river is

$v_{r}b= \sqrt{v_{r}^2 +v_{b}^2 }\\\\(v_{r}b)^2= v_{r} ^2+v_{b}^2 \\\\v_{r}^2=(v_{r}b)^2 - v_{b}^2$.......(I)

Where, $v_{r}b$= resultant velocity of boat with river.

$v_{r}$= velocity of river  

$v_{b}$ = velocity of boat

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

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

$v_{r} = 6 km/hr$

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