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

@iGreen

Answer 2

If the initial height is the ground we can consider as 0, and the initial velocity as 4.9 m/s like the exercise said, then we got\[h=-4.9t^2+vt+s\]\[h=-4.9t^2+4.9t+0\]so\[h=-4.9t^2+4.9t\]Now we need to think "When the ball will back to the ground?!", if it has to back to the groud, so the height will be 0 again, therefore h=0\[0=-4.9t^2+4.9t\]\[0=4.9t*(-t+1)\]the ball will be on the ground when t=0 and -t+1=0\[t_1=0~~and~~t_2=1\]

Answer 3

thanks

Answer 4

You're welcome ;)