We wil have the following:
First, we will determine the travel time:
[tex]400m=(0m)+(0m/s)t+\frac{1}{2}(9.8m/s^2)t^2\Rightarrow t^2=\frac{2(400m)}{(9.8m/s^2)}[/tex][tex]\Rightarrow t^2=\frac{4000}{49}s^2\Rightarrow t=\frac{20\sqrt[]{10}}{7}s[/tex][tex]\Rightarrow t\approx9.0s[/tex]Now, we find the velocity after that time:
[tex]v=(0m/s)+(9.8m/s^2)(20\sqrt[]{10}/7s)\Rightarrow v=28\sqrt[]{10}m/s[/tex][tex]\Rightarrow v\approx88.5m/s[/tex]So, it will have approximately 88.5 m/s.
