DeSean throws a ball up with an initial vertical velocity of 30 feet per second from a platform that is at ground level. How long will the ball be in the air?

Answer 1

h=ho+vi*t-4.9t^2
h=ho=0

0=vi*t-4.9t^2= t(vi-4.9t)

t= 30/4.9 m/s