What Angle Should a Boat Point Upstream to Cross a River Straight?

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SUMMARY

The problem involves determining the angle at which a boat must be pointed upstream to cross a river straight, given a boat speed of 4.0 km/h in still water and a current speed of 1.8 km/h. The correct angle to point the boat upstream is 39°. This conclusion is derived from vector analysis, where the boat's velocity relative to the water must counteract the river's current to achieve a straight crossing.

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Homework Statement


A boat that can travel at 4.0 km/h in still water crosses a river with a current of 1.8 km/h. At what angle must the boat be pointed upstream to travel straight across the river? In other words, in what direction is the velocity of the boat relative to the water?

1. 27° upstream
2. 33° upstream
3. 37° upstream
4. 39° upstream


Homework Equations



V= D/T?

The Attempt at a Solution



i found a problem similar in the book but the answer doesn't make any sense. I have an exam over this material tomm and would really apppreciate if someone can demonstrate and help me understand the solution!
 
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