Question

Water current in a river from east to west has speed
of 4 m/s. A boat staris moving at 10 m/s from south
bank to reach north bank. If boat started at 30° with
current, the drift of boat in crossing 40 m wide river
is nearly​

Answer 1

The Drift is Nearly 37.28 m

Explanation:

Refer to Figure  

Suppose the Angle of travel of Boat be 30° in flow direction

& The Speed (v) = 10 m/s

Time taken to cross the River of width 40 m $=\frac{40}{10\times{sin30\degree}}\\=\frac{40}{10\times0.5}\\=\frac{40}{5}$

Now, The drift in West-East Direction from Initial Point  

$=({vcos30\degree-4})\times{8}=({10}\times\sqrt{3/2 - 4})\times8= 37.28m$

Hence, Drift is 37.28  m