Question

The function y=-16t^2+486 models the height y in feet of a stone t seconds after it is dropped from the edge of a vertical cliff. How long will it take the stone to hit the ground? round to the nearest hundreadth of a second.

Answer 1

Well you know that when the stone hits the ground...the height is then 0 right? so y = 0

\[\large 0 = -16t^2 + 486\]
\[\large 16t^2 = 486\]

Solve for 't'