I understand that gravity acts upon objects at a fairly steady rate on earth. How could I calculate the time in the following example: An object falls ten centimeters before hitting the ground. How much time has passed from when it fell to when it hit the ground? I can't use a stopwatch because the distances are so small. Since gravity is a constant (9.8 m/s2), how can I calculate the time over such a short distance? I'm sure that a computer could calculate this almost instantly, but I would like to know how to perform the calculation on paper.