Question

A firecracker shoots up from a hill 160 feet high with an initial speed of 90 feet per second. Using the formula H(t) = −16t2 + vt + s, approximately how long will it take the firecracker to hit the ground?

Answer 1

I know the answer is 7. But why?

Answer 2

you'll need to replace H(t) with 0 so you'll need to solve the equation: \[\huge 0=-16t^2+90t+160 \]

Answer 3

Ok! Thanks!