Answer
$a). 0.43s, $
$b). 3.5 m/s.$
Work Step by Step
a). $S=ut+\frac{1}{2}at^{2}$
$0.9=0+0.5\times9.8t^{2}$
$t=0.4286s$
Total time of flight = $0.43s$
b). Speed = $\frac{1.5}{0.43}m/s=3.5m/s$
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