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What equation should I use?

  1. Nov 8, 2007 #1
    how do you figure out how long it take's an object launched vertically upwards to reach its apex?
    V=29.4 m/s
     
  2. jcsd
  3. Nov 8, 2007 #2
    v(final)= Vo + a(t) (a= -9.8)
     
  4. Nov 8, 2007 #3
    so
    -29.4 m/s = 29.4 m/s + -9.8t?

    -58.8 m/s = -9.8t
    ----------- ------
    -9.8 -9.8

    6s = t to reach apex
     
    Last edited: Nov 8, 2007
  5. Nov 8, 2007 #4
    Vo is given
     
  6. Nov 8, 2007 #5
    no when it reaches its apex (highest point), the ball has a speed of zero
     
  7. Nov 8, 2007 #6
    yeah so it is v(final)=29.4 m/s + a(t)
    but doesn't an object come back down at the same velocity that it went up?
    that is why I thought:
    -29.4 m/s = 29.4 m/s + a(t)
     
  8. Nov 8, 2007 #7
    right, thats true. but thats not what the question asks. It asks when it reaches its highest point, at the highest point the velocity is 0
     
  9. Nov 8, 2007 #8
    okay so then I should set final velocity to = 0 m/s?

    0 m/s = 29.4 m/s + -9.8t
    -29.4 m/s = -9.8 t
    ---------- -------
    -9.8 -9.8

    t = 3 s ?
     
  10. Nov 8, 2007 #9
    anybody?
     
  11. Nov 8, 2007 #10
    yo, thats right
     
  12. Nov 8, 2007 #11
    thanks
     
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