Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Minimize Distance

  1. Jan 17, 2007 #1
    1. The problem statement, all variables and given/known data
    Mike, who i standing on the deck of a yacth that is travelling due west at 6km/h, sees a sailboat sailing southwestat 4km/h, 3km northwest of the yacht. How close to each other do these boats get?


    2. Relevant equations



    3. The attempt at a solution
    My drawing is:
    | A(2.12-4t,2.12-4t)
    | / \
    | / \
    |/__\B(4.24-6t,0)

    Used pythagorean theorem to find t [tex]D^2=(2.12-4t-0)^2+(2.12-4t-(4.24-6t))^2[/tex]

    Correct so far?
     
    Last edited: Jan 17, 2007
  2. jcsd
  3. Jan 18, 2007 #2

    HallsofIvy

    User Avatar
    Science Advisor

    You have sailboat A with a velocity of <-4, -4>. That gives a speed of
    [itex]\sqrt{16+ 16}= 4\sqrt{2}[/itex], not 4. You need to multiply by
    [itex]\frac{\sqrt{2}}{2}[/itex], just like you did with the initial position.

    And it would be a good idea to specifically state, in your final answer, which sailboat is A and which B and how your coordinate system is set up.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook