Solve.
-A ball is thrown downward with an initial velocity of 28 meters per second from a cliff that is 60 meters high. The height of the ball is given by the quadratic equation $h = - 4.9 t ^ { 2 } - 28 t + 120$ where $\mathrm { h }$ is in meters and $\mathrm { t }$ is the time in seconds since the ball was thrown. Find the time that the ball will be 60 meters from the ground. Round your answer to the nearest tenth of a second.
A) $2.7 \mathrm { sec }$
B) $1.7 \mathrm { sec }$
C) $1.8 \mathrm { sec }$
D) $1.6 \mathrm { sec }$

Question

Quizplus · Accepted Answer

To find the time when the ball is 60 meters from the ground, substitute $h = 60$ into the equation and solve for $t$: $60 = -4.9t^2 - 28t + 120$. Rearranging gives $4.9t^2 + 28t - 60 = 0$. Solving this quadratic equation for $t$ yields $t \approx 1.7$ seconds.

Solve -A Ball Is Thrown Downward with an Initial Velocity h=−4.9t2−28t+120h = - 4.9 t ^ { 2 } - 28 t + 120h=−4.9t2−28t+120

Solve
-A Ball Is Thrown Downward with an Initial Velocity $h = - 4.9 t ^ { 2 } - 28 t + 120$