For this case we have an equation of the form: h (t) = (1/2) at2 + vot + h0 Where: a: acceleration vo: initial speed. h0: initial height Substituting values we have: h (t) = - 16t2 + 19t + 110 The initial speed is then: vo = 19 feet / s Answer: The initial velocity when the rock is thrown is: vo = 19 feet / s