Physics
posted by Sarah .
A student standing on the ground throws a ball straight up. The ball leaves the student's hand with a speed of 11 m/s when the hand is 1.8 m above the ground. How long is the ball in the air before it hits the ground? (The student moves her hand out of the way.)

hf=hi+ vi*t4.9t^2
0=1.8+11t4.9t^2
solve the quadratic equation for t. 
2.39