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A boat is rowed across a river at the ra...

A boat is rowed across a river at the rate of `4.5(km)/(hr)`. The river flows at the rate of `6(km)/(hr)`. The velocity of boat in `(m)/(s)` is:

A

`3.1`

B

`2.1`

C

`2.9`

D

5

Text Solution

Verified by Experts

The correct Answer is:
B
`V_("boat.ground")=4.5(km)/(m)`
`V_("river,ground")=6(km)/(h)`
`V_("boat,ground")=(6hati+4.5hatj)(km)/(m)=(6hati+4.5hatj)xx(5)/(18)m`
`V_("boat,ground")=sqrt(6^(2)+4.5^(2))xx(5)/(18)`
`=1.5xx5xx(5)/(18)=(37.5)/(18)=2.1(m)/(sec)`
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