physics please help

posted by Georgy

A hoodlum throws a rock straight down from the roof of a building 109m high. If it takes 2.40s to hit the ground below, with what initial speed was the rock thrown?

Please show all work

  1. Steve

    If thrown down with initial velocity v, then just solve

    109 - vt - 4.9t^2 = 0

    plug in t=2.40 and find v.

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