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Homework Help: General physics urgen help

  1. Mar 17, 2008 #1
    The ball takes off at 30deg and lads 40 ft from there.
    [Don't solve/calculate the problem, just set up axes, and make a list of what you know or don't: delta-x, delta-y, horizontal velocity, initial vertical velocity, v sub-y, a sub-y, and t.]

    is this correct?:
    delta-x = 40 ft
    delta-y = 0
    horizontal velocity = unknown
    initial vertical velocity = ??? [i dunno!]
    v sub-y = ??? [i dunno!]
    a sub-y = 9.8 [is it positive or negative gravity?]
  2. jcsd
  3. Mar 17, 2008 #2


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    Welcome to PF!

    Hi lifeisamazing! Welcome to PF! :smile:

    Let's see: do you know delta-y … does the problem specifically say that the ball starts on the ground?

    (A ball usually starts by being thrown from someone's hand, several feet higher than it lands!)

    v sub-y is the initial vertical velocity, isn't it?

    Do you know any relationship between the horizontal velocity and the initial vertical velocity?
    Careful! The distance are in feet, so the figure for gravity must be … ? :smile:

    As for positive or negative … which direction is it acting in?
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