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Homework Help: Saving Earth from Asteroid

  1. Jan 12, 2014 #1
    1. The problem statement, all variables and given/known data

    A car drives north at 40mi/h for 10mins then turns east and goes 5min at 60mi/hr. Finally it goes southwest at 30mi/h for 6min.
    a) determine the displacement
    b)average velocity for this trip

    3. The attempt at a solution

    x-component: 60mi/hr/60min x 5min = 5mi
    y-component: 40mi/h/60min x 10mins = 6.7mi

    x-component:[(-30mi/hr cos 45°)/60mins]6min = -2.12mi
    y-component: [(-30mi/hr sin 45°)/60mins]6min = -2.12mi

    a) x-displacement: 5mi + (-2.12mi) = 2.88mi i
    y-displacement: 6.7mi + (-2.12mi) = 4.58mi j
  2. jcsd
  3. Jan 12, 2014 #2


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    hi negation! :smile:
    yes, that looks fine, except i think they expect you to finish by converting into a total distance and a direction :wink:

    (by "direction" i don't know whether they want an angle, or whether specifying a unit vector would be enough)

    (i assume you're ok on b)?)

    EDIT: just noticed …

    how does this save earth from an asteroid?? :confused:
  4. Jan 12, 2014 #3
    Correct me if I am wrong, but displacement means the distance between the starting point and the destination, therefore not the total ground covered.

    Yeah, what does the asteroid have to do with it? :O
  5. Jan 13, 2014 #4

    Sorry it was a careless blunder as to the title.
    Question has been solved
  6. Jan 13, 2014 #5


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    careless blunder?!

    it won't always be a practice! :rolleyes:

    whole planets have been lost for less! :frown:
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