ATRACTOR

The applet is made up of what we call the viewing area (with a gray background) and menus with buttons, text boxes and value control bars (with a blue background). However, it is worth noting that, as we will see later, in some cases it is possible to also enter data directly into the display 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 five areas:

• In the area on the left, two pendulums are represented, formed by two balls of masses m and m, suspended by two rigid rods of length L and L, subject to friction and the action of gravity, of values q and g, respectively. Drag the balls with the mouse to the desired starting position;

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

  Dragging the mouse in this area vertically allows to zooming;

• in the right area (from top to bottom):
  • a three-dimensional representation of the movement of the two pendulums (you can choose the point of view with the mouse);
  • graphs of the angles that the pendulums make with the vertical, as a function of time t;
  • the vector of the initial velocities of the two pendulums.

The initial parameters of the pendulums can be modified:

• in the case of the value of the initial angle that the pendulum makes with the vertical direction,
  • directly in the text boxes: and ;
  • dragging the balls of each of the pendulums;

• in the case of the value of the initial velocity,
  • directly in the text boxes: and ;
  • clicking in the right area at the bottom, defining a new vector (since the cursor has the shape : more details).

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

  

  

  

   

  • dragging the control bars.

  

Once these values have been chosen, click on the button , 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 the lower right area of ​​the applet, always check that the mouse cursor has the following shape: . If it has another shape like , first click . If it is 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 three areas on the right 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, it 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*.