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Homework Help: Vectors in physics

  1. Sep 17, 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 deg west of north with a speed of 6.5 km/h for 15 mins, then due east with a speed of 12 km /h for 7.5 mins. She completes the final leg of her trip in 22 mins. What are 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)

    So I know how to do it, but i am having a bit of trouble trying to figure out the diagram...

    can you tell me if it's a right angle triangle?
    which angles do i use?

    thanks =)
  2. jcsd
  3. Sep 17, 2009 #2
    Well, the first vector goes 25* N of W. So, draw a straight line going up, representing north. Next, draw a diagonal line going to the west but having the same starting point as the line to the north. The angle you just made is the 25* N of W, so it's 25*. Finally, she goes due east, which is a straight horizontal line right. The angle that line makes with the north line is 90*. The north line is now also the final leg of her trip.

    With I could draw a diagram myself to help you, but I can't, so I hoped I helped.
  4. Sep 18, 2009 #3


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    Staff Emeritus
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    It is not necessarily a right triangle.

    See pbdude's response.

    Also, you'll need to figure out the distances traveled in each of the 1st two legs.
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