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Homework Help: Boat problem going across the stream help please

  1. Sep 29, 2010 #1
    A woman who can row a boat at 6.5 km/h in still water faces a long, straight river with a width of 6.1 km and a current of 3.4 km/h. Let point directly across the river and point directly downstream.
    (a) If she rows in a straight line to a point directly opposite her starting position, at what angle to must she point the boat?
    i was thinking here the opposite would be the current 3.4 divided by the velocity of the boat which is 6.5 so sin(x)=(3.4/6.5) then sin inverse of (3.4/6.5) but i get this wrong. any clues?

    (b) If she rows in a straight line to a point directly opposite her starting position, how long will she take?
    in this problem i think we can use D=v*t and put D/V=T to find time. am i right? but i would need the angle from above to complete this.

    (c) How long will she take if, instead, she rows 3.2 km down the river and then back to her starting point?
    min

    (d) How long if she rows 3.2 km up the river and then back to her starting point?
    min


    (e) At what angle to should she point the boat if she wants to cross the river in the shortest possible time?
    °

    (f) How long is that shortest time?
    min
     
  2. jcsd
  3. Sep 29, 2010 #2
    i was able to get all except for a and b if someone could please be of an assistance
     
  4. Sep 29, 2010 #3

    fzero

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    Science Advisor
    Homework Helper
    Gold Member

    The math is right, so you're probably confusing radians with degrees on your calculator.
     
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