You throw a ball downwards with a speed of 10 m/s. It hits the ground 4 meters below from where you threw it. How long is the ball in the air and what is the ball’s velocity just before it hits?
vf^2=vi^2+2ad where a=9.8m/s^2, vi=10m/s
solve for vf. then,
Vf=vi+gt Vf is negative, vi is -10, g is -9.8m/s^2 solve for t