If a ball is thrown upward at 19.6 meters per second from the top of a building that is 70 meters high, the height of the ball can be modeled by $S = 70 + 19.6 t - 4.9 t ^ { 2 }$ meters, where t is the number of seconds after the ball is
Thrown. What is the ball's maximum height?
A) 70 m
B) 128.8 m
C) 84.7 m
D) 89.6 m

Question

Quizplus · Accepted Answer

The maximum height is found at the vertex of the parabola represented by the equation. The time at which the maximum height occurs is $ t = -\frac{b}{2a} = -\frac{19.6}{2(-4.9)} = 2 $ seconds. Substituting $ t = 2 $ into the equation gives $ S = 70 + 19.6(2) - 4.9(2)^2 = 89.6 $ meters.

If a Ball Is Thrown Upward at 19 S=70+19.6t−4.9t2S = 70 + 19.6 t - 4.9 t ^ { 2 }S=70+19.6t−4.9t2

If a Ball Is Thrown Upward at 19 $S = 70 + 19.6 t - 4.9 t ^ { 2 }$