PURPOSE: A brainteaser problem using a string.

DESCRIPTION: A picture is supported by a string from two pegs, as seen in the photographs below from the left and right sides respectively. The interesting thing about how the support is strung is that if you pull the string off either pin the whole thing comes off both pins and the picture falls, as can be seen when you click your mouse on either of the two photographs.

Note that in the video Gwen has positioned her fingers so that only the end that she pulls can slip over the tip of the pin; the opposite side, in both cases, cannot come over the end of the pin.

SUGGESTIONS: See if you can get your students to figure out how to do it, then show them - if you can figure it out.

See Question of the Week #118 for information on using this demonstration to enhance class involvement.

REFERENCES: (PIRA unknown.)

EQUIPMENT: Framed photograph with string and two-pin support mechanism.

SETUP TIME: 5 min.