Solve the problem.
-A projectile is thrown upward so that its distance above the ground after $t$ seconds is $h = - 10 t ^ { 2 } + 320 t$ After how many seconds does it reach its maximum height?
A) $32 \mathrm {~s}$
B) $16 \mathrm {~s}$
C) $8 \mathrm {~s}$
D) $24 \mathrm {~s}$

Question

Quizplus · Accepted Answer

The maximum height of a projectile in the form $h = -at^2 + bt + c$ is reached at $t = \frac{-b}{2a}$. Here, $a = -10$ and $b = 320$, so $t = \frac{-320}{2(-10)} = 16$ seconds.

Solve the Problem ttt Seconds Is h=−10t2+320th = - 10 t ^ { 2 } + 320 th=−10t2+320t

Solve the Problem $t$ Seconds Is $h = - 10 t ^ { 2 } + 320 t$