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Homework Help: Help a highschooler with physics homework?

  1. Sep 14, 2006 #1
    We just started vectors today and introduced the I and J axes. He insists we use I and J instead of X and Y, thats okay.

    So basically here is the question asked:

    A person riding a bike has a velocity v=32m/s I + 12m/s J. Determine the magnitude of hte velocity and hte bikes direction. Determine the total distance traveled by the person on the bike after 120 seconds.

    SO my first step I would think is to draw quadrant 1 of an XY plane. Is the direction northeast? I would imagine this is the case because there is no mention of any negative velocities, so quadrant 1 is + in both axes.
    TO determine the magnitude of velocities...
    Do I simply draw a right triangle, with point (0,0) as the vertex with a 90 degree? Move up 32 in the I, and 12 in hte J?
    Then use A^2+B^2=C^2 to find the hypotenuse? The hypotenuse being the magnitude?

    I THINK that part I have right. BUt it is the total distance that stumps me, can somebody give some insight?
  2. jcsd
  3. Sep 14, 2006 #2


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    Staff Emeritus
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    Gold Member

    You're correct about how to find the magnitude of the velocity.

    Keep in mind that "the magnitude of the velocity" is a fancy way of saying "speed." Once you've found the speed, just multiply it by time to get distance.

    - Warren
  4. Sep 14, 2006 #3
    oooh, that threw me off. Speed makes it all come together in my mind :). Well now, I get 34.18m/s as a magnitude of velocity. So x 120 and 4101.6m

    Thanks! I will have more questions to come tomorrow I am SURE
  5. Sep 14, 2006 #4


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    Excellent homework post. By the way, there's a forum dedicated to those somewhere around here...
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