Question

A river is flowing from west to east at speal a 5m/min. A man on the South Bank of the river capable of swimming at 10 M per minute in still water wants to swim across the river in the shortest time he should swin in a direction

Answer 1

To cross the flowing river in shortest time,the man should swim in the direction of north-east

Answer 2



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A river is flowing from west to east at speed of 5 m/minute . A man on south bank of river, capable of swimming at 10 m/min in still water, wants to swim across river in shortest time. He should swim in direction a)due north. b)30 east of north. c) 30 north of west. d) 60 east of north. Justify you answer.

8 years ago

Answers : (3)

 

 

-------------> V river = 5m/min     

V man = 10 m/minsuppose width of river is x mts

Case 1

if he travels due north

then his resultant velocty ( due to velocity of downstream of water) acts 30 north of east and the distane to be covered to reach the other bank increses to = x/cos 30

i.e., 2x /31/2 and resultant velocity is 11.2 m/min

so time taken is x / 9.7 mins

Case 2

if he travels due 30 north of east

then his resultant velocty ( due to velocity of downstream of water) actsdue north and the distane to be covered to reach the other bank will be x mts and resultant velocity is 8.7 m/min

so time taken is x / 8.7 mins

So case 1 takes least time

he should travel due north(a)

please make my answer as brainlist answer