approach your problems with the theory behind the code .

"As an object falls, its speed increases
because it's being pulled on by gravity.
The acceleration of gravity near the earth
is g = -9.81 m/s^2. To find out
something's speed (or velocity ) after a
certain amount of time, you just multiply
the acceleration of gravity by the amount
of time since it was let go of"

this is how the equation for calculating a falling object's velocity is described by a physics site , therefore given the theory and equations , you need simply the correct values to plug in to the equations under the correct conditions .

if you ever face a problem , remember that there are real world answers , to approach it .