Question

a river 400 m wide is flowing at the rate of 2 metre per second .A Boat is sailing at velocity of 10 metre per second with respect to the water ,in a direction perpendicular to the river. time taken by the boat to reach ithe opposite Bank is

Answer 1

width= 400m
Velocity of the river Vr= 2m/s
velocity of the boat with respect to water Vbr = 10m/s
time= ?
time = d/√Vbr²- Vr² d
$\frac{400}{ \sqrt{ 10 { }^{2} - 2 {}^{2} } }$

= 400 / √10²- 2²
= 400/√96
= 400/9.79
= 40.85 second