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Homework Help: 1d Kinematics formula question

  1. Feb 8, 2006 #1
    Could someone please help me in determine the correct formula(s) to answer this problem?

    A helicopter is ascending vertically with a speed of 2.50 m/s. At a height of 120 m above the Earth, a package is dropped from a window. How much time does it take for the package to reach the ground?

    I know:
    Acceleration -9.8 m/s/s
    Initial position 120m
    Final postion 0m
    velocity 2.50m/s

    I need to determine time.

    Would 2.50/-9.8 give me the correct time of .26 seconds or have I missed something here?

    or would I use 0=120 + 2.50T + .5(-9.8)T^2 giving the time of 50 seconds?
    Last edited: Feb 8, 2006
  2. jcsd
  3. Feb 8, 2006 #2


    User Avatar
    Science Advisor
    Gold Member

    Does 50 seconds seem reasonable?
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