A ball is thrown vertically upward from the top of a building 112 feet tall with an initial velocity of 96 feet per second. The distance s (in feet) of the ball from the ground after t seconds is 1. After how many seconds does the ball strike the ground?

Respuesta :

Answer:

[tex]t=6.96s[/tex]

Explanation:

From this exercise, our knowable variables are hight and initial velocity

[tex]v_{oy}=96ft/s[/tex]

[tex]y_{o}=112ft[/tex]

To find how much time does the ball strike the ground, we need to know that the final position of the ball is y=0ft

[tex]y=y_{o}+v_{oy}t+\frac{1}{2}gt^{2}[/tex]

[tex]0=112ft+(96ft/s)t-\frac{1}{2}(32.2ft/s^{2})t^{2}[/tex]

Solving for t using quadratic formula

[tex]t=\frac{-b±\sqrt{b^{2}-4ac } }{2a}[/tex]

[tex]a=-\frac{1}{2} (32.2)\\b=96\\c=112[/tex]

[tex]t=-0.999s[/tex] or [tex]t=6.96s[/tex]

Since time can't be negative the answer is t=6.96s