| Energy Change Bars Tool: The Energy Change Bars Tool plots colored bars that display the work done on a body and the changes in the body's kinetic, gravitational potential and elastic potential energies since the start of the last simulation. This tool only plots in Run mode. Place an energy bars tool by first selecting the target body, then clicking on the Energy Bars button, and finally clicking at the desired position of the bar graph. You can later reposition the energy bars tool. In the energy bars tool's Properties Box, you can set: Refresh time. How often the tool redraws the energy bars. The default value is 0.2 sec. The shortest refresh time, 0.1 sec, means the energy bars have the same temporal resolution as the clock. However, at such a short refresh time, energy readouts are difficult to read. Show energy readouts. Controls whether energies are displayed as numbers as well as bars. Default option is to display the readouts. Minimum mode. Displays the Energy Bars in a small graph . In minimum mode, the Energy Bars tool never shows energy readouts. See the second figure below. Scale mode. You have two choices, auto mode or hand mode. For descriptions of these two modes and what you need to consider in making the choice, see Choosing Scale Mode on the graph tool's help page. Maximum value. Hand mode only: Sets the maximum energy value displayed by the bars. In auto mode, setting this value has no effect. Measure in kJ. Controls whether energy bars and readouts display energies in joules (default) or kilojoules.
The figure to the right illustrates the layout of the Energy Change Bars tool. The bar graph displays the energies for the body element named Parent, which is attached to a vertical spring. |
> Parent is also subject to gravity and an external constant force labeled Child. The Energy Change Bars tool displays the name of the body in the title banner. On the left, it shows the work done on Parent by Child in red. Work done always sums the contribution of all non-potential, external forces, including friction. On the right, Parent's kinetic energy is shown in blue; the gravitational potential energy, in green; and the elastic potential energy of the spring, in gray.
> Minimum mode: The figure to the right displays the same Energy Bars graph shown in the figure above. |