Solve the problem.
-A flare fired from the bottom of a gorge is visible only when the flare is above the rim. If it is fired with an initial velocity of $176 \mathrm { ft } / \mathrm { sec }$, and the gorge is $448 \mathrm { ft }$ deep, during what interval can the flare be seen? $\left( \mathrm { h } = - 16 \mathrm { t } ^ { 2 } + \mathrm { v } _ { \mathrm { O } } \mathrm { t } + \right.$ $\mathrm { h } _ { \mathrm { O } }$.)
A) $0

Question

Solve the problem.
-A flare fired from the bottom of a gorge is visible only when the flare is above the rim. If it is fired with an initial velocity of $176 \mathrm { ft } / \mathrm { sec }$, and the gorge is $448 \mathrm { ft }$ deep, during what interval can the flare be seen? $\left( \mathrm { h } = - 16 \mathrm { t } ^ { 2 } + \mathrm { v } _ { \mathrm { O } } \mathrm { t } + \right.$ $\mathrm { h } _ { \mathrm { O } }$.)
A) $0 < t < 4$
B) $8 < t < 11$
C) $4 < \mathrm { t } < 7$
D) $12 < t < 15$

Quizplus · Accepted Answer

The flare is visible when its height $ h $ is greater than 0. Solving $-16t^2 + 176t - 448 > 0$ gives the interval $4 < t < 7$.

Solve the Problem 176ft/sec176 \mathrm { ft } / \mathrm { sec }176ft/sec

Solve the Problem $176 \mathrm { ft } / \mathrm { sec }$