12-218 - 12218 The man can row the boat in still water with a speed of 5 m> s If the river is flowing at 2 m> s determine the speed of the boat and the

# 12-218 - 12218 The man can row the boat in still water with...

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12–218.The man can row the boat in still water with a speed of. If the river is flowing at , determine the speedof the boat and the angle he must direct the boat so that ittravels from Ato B.u2 m>s5 m>sSOLUTIONSolution IVector Analysis:Here, the velocity of the boat is directed from Ato B. Thus,. The magnitude of the boat’s velocity relative to theflowing river is . Expressing ,, and in Cartesian vector form,we have ,,and .Applying the relative velocity equation, we haveEquating the iand jcomponents, we have(1)(2)Solving Eqs. (1) and (2) yieldsAns.Solution IIScalar Analysis:Referring to the velocity diagram shown in Fig.aand applying thelaw of cosines,Choosing the positive root,Ans.Using the result of