Question

a river 200 m wide is flowing at the rate of 4 metre per second .a Boat crosses the river in minimum time. if velocity of the boat in still water is 8 metre per second ,then how far from the point directly opposite to the starting point does the boat reach?

Answer 1

Here the boat moves with the resultant velocity R. But the vertical component 10 m/s takes him to the opposite shore. Tan θ = 2/10 = 1/5 Velocity = 10 m/s distance = 400 m Time = 400/10 = 40 sec. b) The boat will reach at point C. In ∆ABC, tan θ = BC/AB = BC/400 = 1/5 ⇒ BC = 400/5 = 80 m.

Answer 2

Explanation:

here is the answer. equate tan(theta) in two cases. so it is 1000m