Solve.
-A ball is thrown upward with an initial velocity of 35 meters per second from a cliff that is 90 meters high. The height of the ball is given by the quadratic equation $h = - 4.9 t ^ { 2 } + 35 t + 90$ where $h$ is in meters and $t$ is the time in seconds since the ball was thrown. Find the time it takes the ball to hit the ground. Round your answer to the nearest tenth of a second.
A) $9.2 \mathrm { sec }$
B) $9.7 \mathrm { sec }$
C) $14.2 \mathrm { sec }$
D) $8.7 \mathrm { sec }$

Question

Quizplus · Accepted Answer

The ball hits the ground when $h = 0$. So, we solve the equation $-4.9 t ^ { 2 } + 35 t + 90 = 0$. Using the quadratic formula, we get $t = 9.2$ or $t = -1.9$. Since time cannot be negative, the ball hits the ground after $9.2$ seconds.

Solve -A Ball Is Thrown Upward with an Initial Velocity h=−4.9t2+35t+90h = - 4.9 t ^ { 2 } + 35 t + 90h=−4.9t2+35t+90

Solve
-A Ball Is Thrown Upward with an Initial Velocity $h = - 4.9 t ^ { 2 } + 35 t + 90$