Answer:
t = 2 s
Explanation:
As we know that when object comes back to its initial position then the displacement of the object will be zero
so here we can say by kinematics equation
[tex]\Delta y = v_y t + \frac{1}{2}at^2[/tex]
here we know that
[tex]\Delta y = 0[/tex]
[tex]v_y = 9.8 m/s[/tex]
[tex]g = -9.8 m/s^2[/tex]
now from above equation we know
[tex]0 = 9.8 t - \frac{1]{2}9.8 t^2[/tex]
so from above equation we have
t = 2 s