Answer: -17.7 m/s
The maximum height achieved by balloon, [tex]s=16 m[/tex]
The instantaneous velocity at the maximum height, [tex]u=0[/tex]
The balloon free falls under gravity, [tex]a=9.8m/s^2[/tex]
Using the equation of motion:
[tex]v^2-u^2=2as[/tex]
where, [tex]v[/tex] is the final velocity, [tex]u[/tex] is the initial velocity, [tex]a[/tex] is the acceleration and [tex]s[/tex] is the distance covered.
Substitute the values:
[tex]v^2-0=2\times 9.8 m/s^2 \times 16 m[/tex]
[tex]\Rightarrow v=\sqrt{313.6 m^2/s^2}=\pm 17.7 m/s [/tex]
We will consider only the negative value, as the positive direction is considered upwards.
