Solve the problem.
-A ball is thrown vertically upward from the top of a building 144 feet tall with an initial velocity of 128 feet per second. The distance s (in feet) of the ball from the ground after t seconds is $$\mathrm { s } = 144 + 128 \mathrm { t } - 16 \mathrm { t } ^ { 2 }$$ . After how
Many seconds does the ball strike the ground?
A) 9 sec
B) 145 sec
C) 11 sec
D) 8 sec

Question

Quizplus · Accepted Answer

The ball strikes the ground when $s = 0$. Setting the equation to 0 gives $0 = 144 + 128t - 16t^2$. Solving this quadratic equation for $t$ when $s = 0$ gives $t = 9$ seconds.

Solve the Problem s=144+128t−16t2\mathrm { s } = 144 + 128 \mathrm { t } - 16 \mathrm { t } ^ { 2 }s=144+128t−16t2

Solve the Problem $\mathrm { s } = 144 + 128 \mathrm { t } - 16 \mathrm { t } ^ { 2 }$