A river of width 200 m is flowing from west to east with a speed of 
. A boat, moving with speed of 
in still water, is made to travel one-round trip (bank to bank of the river). Minimum time taken by the boat for this journey and also the displacement along the river bank are 
and 
respectively.
Text Solution
Verified by ExpertsC
Width of the river 
.
Speed of river 
.
Speed of boat in still water 
.
For minimum time to cross the river, the boat must head perpendicular to the river flow (at 
to the bank).
Time taken to cross once 
.
For a round trip (bank to bank and back), the total minimum time is 
.
During the first crossing, the drift (displacement along the bank) is 
.
During the return trip, to minimize time, the boat again heads perpendicular to the flow relative to the water. The river continues to flow in the same direction, so the drift is again in the same direction as the first trip.
Return drift 
.
Total displacement along the river bank 
.
Thus, minimum time is 40 s and displacement is 200 m .
Prepare Smarter with CGP Edu
Get practice questions, solutions, and test series in one place.
Write a Review
Share your experience with this question and solution.
Commentary
Send your comment, doubt, correction, or feedback to admin.
Similar Questions
Explore conceptually related problems