# The impatient boatman

**Classical Mechanics**Level pending

So he hires a speedboat which has speed'\({ v }_{ B }\)'(in still water) equal to that of the river '\({ v }_{ r }\) ' .

He reckons that to reach there in the shortest time , his boat should always point towards the lighthouse.He reaches the opposite bank at D.

Find distance CD(in km).

Details and Assumptions

\(\rightarrow\) \( { v }_{ r }\)=5 km/hr

\(\rightarrow\) d=1km