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Velocity/direction and vectors!

  1. Feb 5, 2009 #1
    1. The problem statement, all variables and given/known data
    An off-roader explores the open desert in her Hummer. First she drives 25 degrees west of north with a speed of 6.5 m/h for 15 minutes, then due east with a speed of 11m/h for 7.5 minutes. She completes the final leg of her trip in 22 minutes.

    Part A
    What is the direction and speed of travel on the final leg? (Assume her speed is constant on each leg, and that she returns to her starting point at the end of the final leg.)
    Express your answer using two significant figures.
    ANSWER: = ?
    degrees south of west

    Part B
    Express your answer using two significant figures.
    Express your answer using two significant figures.
    ANSWER: = ? m/h

    I dont even know where to start. I tried drawing it out then using trig to get the angles (my answer didnt work). I also used pythag theorum to get the other side of the triangle she makes with her vehicle, but that answer didnt work either >_< would love some help, or even just a explanation to where to start the problem
    Last edited: Feb 5, 2009
  2. jcsd
  3. Feb 5, 2009 #2


    User Avatar
    Science Advisor

    None of your speeds have any units on them... but whatever.

    Perhaps it would help if you were to break this down into three seperate sets of motion:
    1st while she is driving 25ยบ W of N (find out the x and y displacements)
    2nd, while she is driving E (the same)
    And finally, the last leg.

    You should know now how far from the starting point she is and assuming she drives in a straight line draw a picture to that effect. This should help :)
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