Answer: 3.26 s
Explanation:
Given
The ball is projected upward with a velocity  [tex]u=16\ m/s[/tex]
Using the equation of motion
[tex]s=ut+\frac{1}{2}at^2[/tex]
Here, displacement is zero as the ball returns to its initial position
[tex]\Rightarrow 0=16\times t-0.5\times g\times t^2\\\Rightarrow t(16-0.5\times 9.8\times t)=0\\\text{i.e.}\ t=\dfrac{16}{4.9}=3.26\ s[/tex]
the velocity of the ball at any instant is given by
[tex]v=u+at\\v=16-9.8t[/tex]
