Answer:
7 seconds
Step-by-step explanation:
A firecracker shoots up from a hill 140 feet high with an initial speed of 100 feet per second. Using the formula H(t) = −16t^2 + vt + s
v is the initial speed and s is the initial height
Initial speed v= 100 and initial height = 140
So the equation becomes H(t) = −16t^2 + 100t + 140
When the firecracket hit the ground the height becomes 0
So we plug in H(t) for 0 and solve for t
Apply quadratic formula
a= -16, b= 100, c= 140
t=-1.18 or t= 7.43
it take 7 seconds for the firecracker to hit the ground