A boat can move at exactly 5 m s-1 through water flowing east at 3 m s-1. It is to travel due north

Question

A boat can move at exactly 5 m s-1 through water flowing east at 3 m s-1. It is to travel due north relative to land across a river 80 m wide. Find its required water-relative velocity and crossing time. Explain whether the same direct crossing is possible if the eastward current increases to 6 m s-1.

Accepted Answer

$-3\mathbf i+4\mathbf j\text{ m s}^{-1};\quad20\text{ s};\quad\text{impossible with the stronger current}$

Feasibility of a direct crossing

Feasibility of a direct crossing

Solution:

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