To find out distance between any given two points, simply drag the ruler and measure the distance. At the top of simulation you can see a summary of projectile motion, it shows total flight time, total horizontal displacement and vertical displacement. Notice that end result of vertical displacement is around -1.2 meters, that because projectile initially fired 1.2 meters above ground level. You can change initial height of projectile by dragging cannon.
Initial angle of project you can either enter in left side property window or you can drag and rotate canon to change angle.
If your settings will generate long range or short range projectile, please use zooming tool to fit your projectile path to screen to get a better picture of motion.
Vi = Initial velocity
Vf = Final velocity
Vx = Horizontal velocity component
Vy = Vertical velocity component
a = Acceleration
t = time
H = Peak height
X = Horizontal displacement
This video requires Flash Player 9
PhET Interactive Simulations
University of Colorado