Question

The function y = –16t2 + 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 hundredth of a second.

Answer 1

Since we are looking for the time it takes for the stone to hit the ground, then it means that we set the height y to 0 ft.

y = -16t² + 486
0 = -16t² + 486
16t² = 486
t² = 30.375
t = 5.51 seconds