Low Cost Apparatus
Apparatus Title: Axial Vectors: a Corridor Display
A clock with a transparent face is placed in front of a plane mirror. The angular velocity vector of the clock's second hand is directed into the clock's face, so when the clock is facing away from the mirror, the angular velocity vector of its second hand is directed toward the mirror. Curiously, the angular velocity vector of the image of the second hand is in the same direction. However, if an arrow is directed into a mirror, it's reflection is directed in the opposite direction.
Equipment required to construct apparatus:
Item Source/Store Part Number Cost One wall clock from Walmart Total cost...............................................................$10........ ....$
Sketch of the apparatus A complete description of the apparatus is desirable, detailed enough that others can duplicate the apparatus. This description (anonymous) will be available to the judges of the apparatus. Samples of student reports (anonymous) may also help the judges to recognize the merits of this apparatus.
An inexpensive ($4) wall clock is taken apart. The face is Xeroxed onto a transparent plastic sheet, which is then mounted on a 1/8 inch sheet of transparent plastic. The clock mechanism and hands are then mounted on the transparent sheet.
The clock is then placed on a wooden base and a wooden arrow is mounted on the same base. The arrow is normal to the clock face, directed into its center.