Arches - how strong are they?
The materials required for this science fair project are:
- 4 plywood sheets (1 meter x 1 meter)
- 1 large pail
- Tap water
- 1 weighing machine
- 2 fixed pillars 500 mm apart
- 1 saw
- 1 ruler
- 14 bricks (add more bricks as required)
- 1 marker pen
1. The independent variable of this science fair project is the length of the arch. The dependent variable is the amount of weight place on the arch before it breaks. This is determined by measuring the weight of the load using the weighing machine. The constants (control variables) are the distance between the pillar, the type of wood used and the dimension (width and thickness) of the wood.
2. Cut the plywood into smaller pieces, of width 100 mm. Cut 4 pieces of plywood into the following lengths – 500mm, 550mm, 600mm, 650mm, 700mm, 750mm, 800mm and 850mm. Draw a line at the center of the plywood.
3. Two pillars 500mm apart are used as a test table. See figure 1 below. Such a pillar can also be created by arranging the bricks on the sides of a door as shown in figure 1.
4. Position the 500mm peice of plywood as shown in figure 1 Hang the pail on the plywoodwith a string. Use the line marked earlier as a guide for the center. Add water to the pail until the plywood breaks. Record the final volume of the water used.
5. Repeat step 4 on the remaining 7 sizes of plywood. Record the measurements in the table provided below.
Sawing should be performed by an adult wearing proper safety gear.