Answer
a) .4 seconds
b) No--there is still approximately .5 meters before the ball hits the ground.
Work Step by Step
a)
$-b/2a = -3.8/2*-4.9 = -3.8/-9.8 = .3878$
$h=-4.9t^2+3.8t+.5$
$h=-4.9*(.3878)^2+3.8*.3878+.5$
$h=-4.9*.15035+1.47347+.5$
$h=-.736715+1.97347$
$h=1.23675$
b)
$h=-4.9t^2+3.8t+.5$
$h=-4.9(.3878*2)^2+3.8*(.3878*2)+.5$
$h=-4.9*.6015553+3.8*.7756+.5$
$h=-2.9476209+2.94728+.5$
$h=.49966$
