You may provide fast and loose input to this model by using the cursor to set the initial velocity. The magnitude of the velocity and the angle are shown in the left margin. For more precision, you may set the values of angle and speed by clicking on the box where they are displayed and entering the values you set in by pressing on the Enter key. Then just click anywhere on the drawing area to fire the set shot. You may answer questions like how high does the projectile rise and where does it come down by using the cursor and reading off the x and y values. The time required for the projectile to come down is displayed for each shot.
Remember that there are some assumptions underlying this display. One is that acceleration is constant in the -y direction at 9.8m/s^2. Another is that air resistance has no effect on the projectile's motion. The first assumption is reasonable over distances small compared to the radius of the Earth. The second assumption if bogus for any real projectile. It is one of those idealizations that allows us to simplify the math to gain understanding.