Big Progress

Fixed issues with numbers not matching up with variables (now the
picture and the printed values match up)

Made JS code more readable with functions
Added comments to the JS functions

Known bug(s):
pressing the "Start" button twice speeds up the motion and prevents the
"Stop" button from working

Possible features:
a frame-by frame button
a rewind button
a trail behind the ball
bouncing when it hits the ground
user-inputted values for initial conditions