Question

A firecracker shoots up from a hill 165 feet high with an initial speed of 110 feet per second. Using the formula H(t) = -16t2 + vt + s, determine how long it will take the firecracker to hit the ground

Answer 1

put H(t)=0
and s=165
and solve the quadratic equation.

Answer 2

Total distance covered in vertical direction = - 165 ft
Initial velocity in vertical direction = 0 acceleration = -32ft/s^2
using S = ut + 1/2 at^2
-165 = 1/2 x -32 x t^2
t^2 = 165/16
you can calculate time now