Answer: 78.4 m/s
The formula for speed using known acceleration:
[tex]v=at+v_0=gt+v_0[/tex]
where the initial velocity v0 = 0 in this case, g is the gravitational acceleration and t is given to be 8 seconds, so:
[tex]v = 9.8 \frac{m}{s^2}\cdot 8 s=78.4 \frac{m}{s}[/tex]
