The pendulum artist

Pen­du­lums can be artists too!

Safe­ty pre­cau­tions

None.

Equip­ment

• string;
• bot­tle;
• paint;
• pa­per;
• foam rub­ber;
• awl;
• clamp;
• cross­bar;
• wa­ter;
• food col­or­ing.

Step-by-step in­struc­tions

Cut a bot­tle in half. Use an awl to bore two holes in the top half and pass a string through them. Ad­di­tion­al­ly, bore a hole in the cap. At­tach a clamp to the string and tie the string to a straight hor­i­zon­tal cross­bar. The clamp di­vides the sys­tem into two sec­tions. The up­per sec­tion can swing only in one di­rec­tion, while the low­er sec­tion can swing in all di­rec­tions. Use a sheet of foam rub­ber as a can­vas. Pull the pen­du­lum to one side, add some tint­ed wa­ter, and let go. This will re­sult in sym­met­ri­cal pat­terns. You can change the type of pat­tern the pen­du­lum cre­ates by ad­just­ing the po­si­tion of the clamp.

Process de­scrip­tion

As a pen­du­lum is a load sus­pend­ed at a point, it can swing freely in all di­rec­tions. But if the sus­pen­sion point it­self can os­cil­late, the tra­jec­to­ry of such a com­pos­ite pen­du­lum can cre­ate stun­ning pat­terns. The re­sult is a pen­du­lum that si­mul­ta­ne­ous­ly per­forms two har­mon­ic os­cil­la­tions. The tra­jec­to­ries of such a pen­du­lum are called Lis­sajous fig­ures. The type of tra­jec­to­ry is de­ter­mined by the ra­tio of the pe­ri­ods of os­cil­la­tions of the up­per and low­er parts of the pen­du­lum. If this ra­tio is an in­te­ger, the tra­jec­to­ries will be closed. You can use some­thing like this to cre­ate ab­strac­tion­ist pic­tures. Sci­ence is art!