Materials:

Item	Quantity	Price
3/4 inch rigid pulley	2	$0.99
1/2 inch PVC sch 40 pipe	one 8 1/4 inch two 2 3/4 inch	$1.18/10 feet
1/2 inch PVC 90° elbow	2	$1.09/package of ten
10-24 x 1 Round Head Machine Screws with nuts	2	$0.98/ package of 6
3/16 inch, 5 1/2 inch eye hook turnbuckle	1	$1.44
#18 x 800 nylon twine	15 feet	$3.96/800 feet

• Using a 3/16 inch drill bit, drill a hole 3/8 inch below the top of each 2 3/4 inch segment of PVC pipe.
• Attach the pulley to the PVC pipe using the machine srew and nut. Tighten.
• Insert the 2 3/4 inch segments into each of the elbows. Use the 8 1/4 inch segment of PVC pipe to connect the elbows.
• PVC pipe cement can be used to secure the PVC pipe.

Two medium size clips can be attached to the bottom of the long PVC pipe segment as shown to hold the accelerometer. Screws can be used to secure the clip to the PVC pipe or hot glue. If hot glue is used, the clip will snap off easily.

The cost of the String Racer is approximately $4.50/unit.

Activities Using the String Racer

Assembly Directions for Accelerometer

This activity was developed for an AAPT/PTRA workshop, The Role of Toys in Teaching Physics, presented November 13, 1999, in Houston, TX, by Peggy E. Schweiger.