IIT JEE , AIEEE Forum - Physics , Mechanics - River Boat Problems

sachin_gupta1991

Q. A swimmer wishes to cross a 500 m wide river flowing at 5 km/hr. His speed with respect to water is 3 km/hr.

a) if he heads in a direction making an angle

with the flow, find the time he takes to cross river. (ans: 10 min/sin

)

b) find the minimum drift.

Plzzz give detailed sol. with diagram.

SALUTES TO ALL ACCEPTABLE ANSWERS.

Goalie

just remember that the swimmer's velocity perpendicular to the river flow will remain unaffected by river flow.

And the crossing time will depend ONLY upon swimmer's velocity perpendicular to the river flow (hope you got it by now.)

Swimmer's velocity perpendicular to river flow is 3km/hr.* sin

= 50sin

m/min

river is 500 wide . so the time taken to cross river = 500/(50sin

/min)=10/sin

min

hope it satisfies

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