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Homework Help: Velocity vector and Max Height

  1. Mar 5, 2009 #1
    This is a question from "Fundamentals of Physics 8th Edition Extended, Chapter 4, Checkpoint3."

    "At a certain instant, a fly ball has velocity v->=25i-4.9j (the x axis is horizontal, the y axis is upward, and the v-> is in metres per second). Has the ball passed its highest point?

    The answer in the book says it hasn't...????

    But I believe it has as -4.9j means the ball is now falling towards the ground therefore it has past its max height within the projectile motion.

    Am I incorrect, or is the book wrong??, If i'm incorrect can someone point out why?
  2. jcsd
  3. Mar 5, 2009 #2


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    Welcome to PF!

    Hi ProRip ! Welcome to PF! :smile:
    Yup … minus j means it's moving downward …

    looks as if the book is wrong! :redface:
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