Simulator Help

Use the simulator here, or open another in a separate window (using the link above) to examine as you read through the following help page.

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  1. When the applet opens, you will notice that a small introduction screen appears. Please read the text there. You can close the introduction screen using the small X in the top right corner.
  2. The menu in the top left corner allows you to open the Tracing Tool, whch will be discussed below, or to open the small introduction screen again.
  3. Firstly, you should notice the blue mass, m, on the end of a spring resting at equilibrium. You can change the displacement of the spring by dragging the spring, by inputing a value in the box labeled Initial Displacement, or by using the up and down arrows on the Initial Displacement box. You can change the value of the initial velocity of the spring, or by using the box labeled Initial Velocity.
  4. If your desired initial displacement is not in the range of the spring, then you should change the size of the applet using the drop down menu in the top right hand corner of the applet. If you select Defualt Size, the mass can be moved from -1 to 1. If you select 2x, the mass can be moved from -2 to 2; 4x, -4 to 4, 8x, -8 to 8; and 16x, -16 to 16.
  5. There are three sliders located near the top of the page. You can use them to adjust three parameters, mass (m), the damping constant (b), and the spring constant (k). If you would like to input a specific value for any one of these constants, it is easiest to click on the small green number sign. A menu will open where you can input a value which you choose.
  6. Below the slider for the damping constant, a critical damping constant is given. This damping constant is represented on the damping constant slider by a small vertical line. Notice that the critical damping constant changes as the mass and spring constant are varied. If you do not understand the critical damping constant at this time, do not worry, as you will learn about it as you work through one of the modules.
  7. After selecting values for each of the parameters, you can press the Start Simulator button. If you have not selected an initial displacement or initial velocity, a warning will appear promting you to do so. As the simulator runs, you will see three graphs appear at the bottom. You will see a Displacement vs. Time, a Velocity vs. Time, and a Velocity vs. Displacement graph. Study each graph carefully, as they each describe the behaviour of the solution governing the motion of the mass on the spring.
  8. The behaviour of the spring is classified into one of four cases: Undamped Motion, Underdamped Motion, Critically Damped Motion, or Overdamped Motion. The case is shown in a box in the bottom left corner of the simulator.
  9. The solution governing the motion is shown at the bottom of the applet.
  10. It is possible to change the parameters and run the simulator again, but before you do so, you will be promted to Rewind the Simulator and then change the parameters.
  11. Other runs are color coded, as to distinguish between them. You can click on each label in the legend to toggle that run's graphs on or off.
  12. Similarily, you can use the radio buttons below the solution to show the solution for each respective run.
  13. After four runs, you need to reset the simulator (using the Reset Button) to preform more runs.
  14. Lastly, The Tracing Tool is can be used to find the displacement or velocity at a time which the user inputs. It can also be used to show the maximum or minimum displacement. If the tracer displays NaN (Not a Number), do not worry, it is just that the algorthim cannot handle these cases. Normally this occurs when, for example, the maximum displacement is on the y-axis.

Good luck!

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