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Homework Help: Help finding average speed

  1. Sep 17, 2005 #1
    The problem is:

    A motorist drives south at 20.0 m/s for 3.00 min, then turns west and travels at 25.0 m/s for 2.00 min, and finally travels northwest at 30.0 m/s for 1.00 min. For this 6.00-min trip, find (a) the total vector displacement, (b) the average speed, and (c) the average velocity. Let the positive x axis point east.

    I need help figuring out the total vector displacement. I just want someone to explain how you find it and let me work it please.

    thanks for the help
  2. jcsd
  3. Sep 17, 2005 #2
    you can use a cartisen coordinate system to figure out the vectors

    you first travel south for 3600 meters, this would be (0 , -3600)

    then you travel west for 3000 meters, add this to the first you have (3000 , -3600)

    hen you travel 1800 meters at an angle of 45 degrees so you have ( 4272.292 , -2328)

    you can do the rest right
  4. Sep 17, 2005 #3
    That wasn't my question. My question is how do i find the total displacement.
    Do i just add all of that together?
  5. Sep 17, 2005 #4
    yes that should do it
  6. Sep 17, 2005 #5
    Thanks so much for the help. :smile: :rofl:
  7. Sep 17, 2005 #6
    Adding the components will give you the total displacement vector. Are you sure that is what you want?

    Perhaps you were thinking about the magnitude of the vector as well? Do you know how to find this?
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