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Homework Help: Position of body

  1. Mar 22, 2016 #1
    1. The problem statement, all variables and given/known data

    for part b , why when t = 0 , x= 0 , why not x =100 ? the author gave that the object drop from height of 100ft at the start of the question.
    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Mar 23, 2016 #2


    Staff: Mentor

    The author is defining the point at which the object is dropped as x = 0, and the point on the ground as x = 100.
  4. Mar 23, 2016 #3
    Is it wrong to consider x=100 when t=0??
  5. Mar 23, 2016 #4


    Staff: Mentor

    Yes, if you're trying to follow the author's work.
  6. Mar 23, 2016 #5


    User Avatar
    Science Advisor

    There are no "coordinates", x, y, t, etc. automatically given by a physical situation- you define those yourself. Here, where we have an object dropped from a height we can choose to take x to be 0 at the ground, in which case x(0)= 100, or we can choose to take the x to be 0 at the point from which the object was dropped so that x(0)= 0. We can also choose in which direction to take x to be positive or negative.
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