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A man crosses a river in a boat. If he c...

A man crosses a river in a boat. If he cross the river in minimum time he takes `10 min` with a drift `120 m.` If he crosses the river taking shortest path, he takes `12.5 min,` find
(a) width of the river
(b) velocity of the boat with respect to water
(c) speed of the current

A

width of the river is `200 m`

B

velocity of the boat with respect to water `12m//min`

C

speed of the current `20m// min`

D

velocity of the boat with respect to water `20 m//min`

Text Solution

Verified by Experts

The correct Answer is:
A, D
Shortest time Shortest path
`10m=w/v_(br),12.5=v_(r)/((v_(br)cos theta)`
`120=10xxv_(r) 12.5 =10sec theta`
`v_(r)=12m//min cos theta=4/5`
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