A low-cost demonstrator accelerometer can be constructed out of dowel and a Zip-Loc bag. A frame consisting of four straws and four dowels slips into the bag, making it rigid. When filled with colored water, the water "slants," indicating acceleration.

Materials:

• 20 inches of 1/4 inch dowel
  • two pieces 5 1/2 inches long
  • two pieces 4 1/2 inches long
• four flexible straws (those that bend)
• Zip-Loc freezer bag, pint size

Directions for Assembly:

• Fold two of the flexible straws in half. Cut the longer end of the straw even with the shorter end. These will be opposing corners of the frame.
• Cut the long end of the other two straws so that it is 3 3/4 inches long. These will be the other opposing corners of the frame.
• Insert dowel into the straws, forming a rectangle, and insert into the Zip-Loc bag.

The activity was presented by Jim Nelson at the 1999 AAPT/PTRA training workshop held in San Antonio, TX.

Activities Using the String Racer

Assembly Directions for String Racer