Question

A river flows at 3m/s and is 300m wide .A man swims across the river with a velocity of m/s directed always perpendicular to the flow of current .
(i). How long does it take the man to cross the river?
(ii). In what direction does he actually move relative to the shore?
(iii). How far does the stream (from the starting point) does he reach the opposite bank?

Answer 1

Answer:

150 min

33.7°

450 m

Explanation:

Man Velocity = 2 m/s

River Velocity = 3m/s

Net velocity =  √2² + 3² = √13 m/s

Angle with  stream = α

Tanα = 2/3  => α = Tan⁻¹(2/3) = 33.7°

Time taken by man to cross river = 300/2 = 150 min

he actually move 33.7° relative to the shore down the stream he reaches the opposite bank = 150 * 3 = 450 m