Question 247939
It has to do with finding initial velocity from the starting point. 
The qestion is, While on vacation, Ben dropped his glasses over the edge of the Grand Canyon. If he was 384 feet up when the glasses fell, how long till the glasses hit the river below? The equation to set it up is {{{-16t^+vt+(384)}}}
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The initial velocity is zero: Ben simply dropped his glasses.  He didn't
throw them up or down.
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The full equation is h(t) = -16t^2+384
h is the height of the glasses and it is zero when the glasses hit the river.
-16t^2 = -384
t^2 = 24
t = 2sqrt(6) seconds
t is approx 4.9 seconds
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Cheers,
stan H.