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    Re: Need dip-throw a rock?
    From: Frank Reed
    Date: 2011 Jun 22, 20:49 -0700

    Hi Bill, you wrote:
    "If one assumes a timing error of 0.1 seconds (and you don't have to be old and decrepit to have such an error when operating a stop watch)"

    Yep. That's why I mentioned electronic and better yet video timing. It's obvious how the error works here, too. Given that dip=4*time (dip in minutes of arc, time in seconds), then obviously a tenth of a second error in time yields 0.4 minutes of arc error in dip. And it doesn't matter how high you are until you get to really high altitudes where air resistance will start to linearize the fall time, which is the real uncertainty. By the way, if you're projecting your projectile horizontally, you need a pretty good technique for ensuring that it's really horizontal. Hence my suggestion for a slingshot: you can aim it right at the horizon. If there's nothing in the way straight down, of course, there's no need to shoot horizontally --just drop it.

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