# How to Find Speed From Distance & Mass

By Kimberly Dyke

Mathematics instructs us that speed = distance/time. It is possible, however, to calculate speed from a different approach, using distance and acceleration variables, if distance and time are not both available. Speed, or velocity, is determined by: Final velocity squared -- initial velocity squared = 2(acceleration*displacement). Follow the steps and you can determine the speed for your mathematical problem.

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.