ATRACTOR

The applet consists of what we call the display area (with gray background) and menus with buttons, text boxes and value control bars (with blue background). However, it should be noted that, as we will see later, in some cases it is also possible to enter data directly in the visualization area.

Click on the image where you have questions.

Note: The following figures are non-manipulable images. In the figures marked with , if you hover the mouse over them you will see an animation.

The display zone is divided into four areas:

• in the area on the left is a double pendulum formed by two balls of masses m and m, suspended by two rigid rods of length L and L, he second articulated at the end of the first, subject to friction and the action of gravity, of values q and g, respectively . Use the mouse to drag the balls to the desired starting position;

• in the central area, there is a representation of the potential, kinetic and total energies of the pendulum at each instant.

  Dragging the mouse in this area vertically makes it possible to zoom;

• in the right area:
  • above is represented the trajectory in the space of configurations which, in this case, is a torus;
  • Below is the vector of the initial velocities of the two balls.

The initial parameters of the pendulums can be modified:

• in the case of the value of the initial angles that the rods make with the vertical direction,
  • directly in the text boxes: and ;
  • a dragging the pendulum balls;

 

• in the case of initial speed values,

• directly in the text boxes: and ;
• clicking in the lower right area, defining a new vector (as long as the cursor has the shape : more details).

• in the case of the values of lengths (L and L), masses (m and m), friction (q) and gravity (g),
  • entering the values in the text boxes;

  

  

  

   

  • dragging the control bars.

  

Having chosen these values, click , to see the simulation of the pendulum movement.

The menu has the following options:

• : to reset the time value (t = 0);
• : to return to the initial setting.

Important note: to choose a point in one of the areas on the right part of the applet, always check that the mouse cursor has the following shape: . If it has another shape like , click first. If it is in the shape and you want to change to just click with the right mouse button and in the window that appears choose the option Rotate, Orbit.

In the two areas on the right side of the applet, try clicking on them with the right mouse button: you get a menu with other options for manipulating objects.

Among the options, allows you to have a resizable window of the area where you clicked - for more information, click here.

The flag, at the top of the applet, indicates the language used. If you wish, click on it and select another language:

By clicking , you can choose between:

• : access this instruction page;
• : accesses information about the applet version*.