Question

The height in meters of a projectile can be modeled by h = −4.9t2 + vt + s where t is the time (in seconds) the object has been in the air, v is the initial velocity (in meters per seconds) and s is the initial height (in meters). A soccer ball is kicked upward from the ground and flies through the air with an initial vertical velocity of 4.9 meters per second. After how many seconds does it land approximately?

Answer 1

\[
h = −4.9t2 + vt + s \\
v = 4.9 \\
s= 0
\]That gives you a quadratic equation.
Use the quadratic formula to find out when the height is \(0\).
You'll get two answers, since it's a quadratic.
We know one of them is \(t=0\), when the ball is kicked.
We want the other one.