Determine the time, or initial velocity. If that is not available, then the calculation can only be made assuming that it started from rest.
Use the equation, vf^2 -- vi^2 = 2ad, where "vf" represents the final velocity, "vi" is the initial velocity, "a" is acceleration and "d" equals the displacement.
Note that acceleration equals -9.8 meters per second since it is a free fall. The mass amount does not change the formula because all objects accelerate at the same rate when falling downward.
Use the formula, velocity = mass x acceleration, and calculate the final velocity by following these steps:
vf^2 - 0 = 2(-9.8)(-0.05)
vf = root(0.98)
vf = 0.99 m/s
Take the final velocity/speed amount, or 0.99 meters per second, and plug it into the basic formula for speed:
speed = distance/time.