Question 431102
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The height of a projectile in feet at time *[tex \Large t] given an initial velocity of *[tex \Large v_o] and an initial height of *[tex \Large h_o] is given by:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ h(t)\ =\ -16t^2\ +\ v_ot\ +\ h_0]


You have a zero initial velocity and a 196 ft initial height, so:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ h(t)\ =\ -16t^2\ +\ 196]


The ground is height zero, so solve:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -16t^2\ +\ 196\ =\ 0]


Since this is a quadratic, you should get two roots.  One of them will be negative.  Since you don't care what happened BEFORE you dropped your keys, discard the  negative root.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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