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Homework Help: Net displacement

  1. Sep 16, 2014 #1
    1. The problem statement, all variables and given/known data
    I'm have a hard time figuring out how to do this problem:
    A sailboat tacking against the wind moves as follows: 3.8 km at 45° east of north, 4.5 km at 55° west of north, 2 km at 45° east of north. What is the net displacement for the entire motion? How many degrees east of north is the sailboat?

    2. Relevant equations

    3. The attempt at a solution
    I thought that to find the net displacement you had to simply add the vectors:
    3.8+4.5+2=10.3 However, this is not right and I don't understand how else to solve the problem.
  2. jcsd
  3. Sep 16, 2014 #2


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    Adding the vectors is exactly what you are supposed to do, but it's not what you did. You just added the individual magnitudes. You need to draw a diagram of what the boat is doing and go from there.
  4. Sep 16, 2014 #3
    I did draw the picture but I'm not sure what to do with the picture.
  5. Sep 17, 2014 #4


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    Well, see, the thing is, even the best minds here are not mind READERS, so if you don't post it there's not going to be much we can do to help you.
  6. Sep 17, 2014 #5


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    You calculated the distance sailed not the net displacement. Do you understand the difference?
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