Question

Derek kicks a soccer ball off the ground and in the air with an initial velocity of 31 feet per second. Using the formula H(t) = -16t2 + vt + s, what is the maximum height the soccer ball reaches?

14.2 feet

14.6 feet

15.0 feet

15.3 feet

Answer 1

The answer to this question is:

C: 15.0 feet

Answer 2

given v=31 and s=0

H(t) = -16t2 + vt + s

H(t) = -16t^2 + 31t

dH/dt = -32t + 31

At the maximum height, dH/dt = 0

-32t + 31 =0

t = 31/32 = .96875

substitute back to H(t)

H( .96875) = 15.0 ft

ans is C