The height, in meters, of a projectile can be modeled by h= -4.9t^2 + 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 velocity of 4.9 meters per second. Approximately, after how many seconds does it land?

Question

Reiny · Answer

so your height formula is
h = -4.9t^2 + 4.9t + 0 , assuming kicked from ground
when it lands, h = 0
-4.9t^2 + 4.9t = 0
-4.9t(t - 1) = 0
t = 0 ----> at the moment the ball is kicked
or
t = 1, it lands 1 second later

Steve · Answer

it lands when h=0. So, just solve the quadratic the way you do normally.

Cooper · Answer

Thanks!