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At what height objects will pass each other?

  1. Jan 25, 2014 #1
    1. The problem statement, all variables and given/known data

    An object is thrown downward with an initial (t = 0) speed of 10 m/s from a height of 60 m above the ground. At the same instant (t = 0), a second object is propelled vertically upward from ground level with a speed of 40 m/s. At what height above the ground will the two objects pass each other?

    first object
    t0 = 0
    V = 10 m/s
    H = 60
    Second object
    t0 = 0
    V = 40 m/s
    H = 60
    2. Relevant equations
    d = Vi . t + 1/2 a t2


    3. The attempt at a solution
    This equation doesn't see me to work since we need to find at which height objects will pass
     
  2. jcsd
  3. Jan 25, 2014 #2

    tiny-tim

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    hi patelneel1994! :wink:

    call the height of either object above the ground "d", and rememb
    er that the two objects start at different values of d …

    show us what you get :smile:
     
  4. Jan 25, 2014 #3
    So instead of d I should put h. Find height for each object separately!
     
  5. Jan 25, 2014 #4

    tiny-tim

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    d or h, it doesn't matter, so long as you use the same symbol for each, but start them at different values :wink:
     
  6. Jan 25, 2014 #5
    I got 41 m. Thanks
     
  7. Jan 25, 2014 #6

    haruspex

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    I confirm that answer. A slightly quicker way, perhaps, is to note that the two objects undergo the same acceleration, so the relative velocity is constant. The closing speed is therefore a constant 10+40=50 m/s. That tells you how long they take to meet.
     
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