To run this display, click the mouse buton on the screen at a height representative of the initial vertical velocity. Then click the Action buton to start the display. Also in this display I introduce another feature which we will see again in later displays. Down in the lower left hand corner of the display border is the "Elapsed Model Time" clock. Model time differs from real time because the rate of time flow in the model depends on the speed of your computer in calculating the effect of each time slice and displaying the results. In some animated displays, like the ball toss example, I have set the time between frames at 20 miliseconds so each time slice of the model takes at least that long in real time. You may click on the timer label to toggle the clock off and on.