This model represents a tank of fluid with a box 1 meter on each edge so that its volume is 1 cubic meter. The mass of this box may be adjusted by entering a new value in the box mass field. Initially the box is found suspended with its lower face at the surface of the fluid. When it is released by a click on the Action button, it penetrates the fluid to ultimately float or not depending on the relationship between the mass of the box and the density of the fluid as set in the fluid density field. The motion of the box during the model run is affected by flow resistance as determined by the flow resistance coefficient, frc.

The model opens with an animated view of the physical layout of the apparatus we call the lab view. The model first calculates 2000 states that define its behavior over a 20 second period of model time. The array of states, each of which contains a record of object position, velocity, acceleration and other parameters, is stored in memory. The sequence of calculated states is then available to create animation. By using the keyboard up or down arrow key you may scan the states forward or backward through time for a detailed look at model behavior. The default step size for arrow key action is ten time-increments, called chronons. By holding down the shift key while pressing an arrow key you reduce the step size to one chronon. The model window must have the keyboard focus for the arrow keys to be effective. You may click anywhere on the drawing area to give the model window the focus. The status of the arrow keys is displayed in the upper right corner of the drawing area in the lab view.

There is an alternative view of the model output called the graph view. This view is selected in the left margin by clicking the graph button and opens with a graph of the depth of the center of mass of the box vs. time. In the graph view you may toggle on and off the plots of depth, velocity and flow resistance by clicking on the plot legend in the top, right quadrant of the drawing area. Also in the graph view you may zoom in on a particular region of the graph by using the mouse to click and drag a rectangle that will expand to fill the drawing area on release of the mouse button. The B button in the pan/zoom cluster will restore the original drawing area limits.

For details on the operation of applet controls, see the Model Controls help page.