## Domino effect

 Difficulty: Intermediate 6 Cost (\$): 50 Time required: < 3 days 1 day to prepare, 1 hour for the science project experiment Availability of materials: Dominos may be purchased at a toy store Required Skills: None Safety concerns: None
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### Materials

The materials required for the science fair project experiment:
- 100 domino tiles (50mm x 25mm x 6mm)
- 1 measuring tape
- 1 ruler
- 1 stopwatch
- 1 flat floor

### Procedure

1. For this science fair project, the independent variable is the distance between the domino tiles – 10mm, 15mm, 20mm, 25mm, 30mm, 35mm,  or 40mm. The dependent variable is the time taken for the 100 domino tiles to topple over. This is determined by measuring the time using a stopwatch. The constants (control variables) are the size of the domino tiles, the number of tiles used and the weight of the tiles.

2. The 100 domino tiles are arranged in a straight row. The  distance between the tiles is maintained at 10mm. The total distance from the first tile to the last one will be 1584mm. As  the  first tile is knocked over,  the stopwatch is simultaneously started. The first tile will collide with the next one, causing it to topple over. This will continue until the last tile has fallen. The stopwatch should be stopped just as the last tile falls.

3.  Procedure 2 is repeated 5 times and the average time taken is calculated and recorded.

4.  Procedures 2 and 3 are repeated with a distance between tiles of 15 mm, 20 mm, 25 mm, 30 mm, 35 mm and 40 mm. The average amount of time taken for the 100 tiles to topple over is calculated and recorded in the table given below.

5. The speed of the falling tiles is measured using the formulae given below :

Speed of tiles (mm/sec) = Total length of arranged tiles (mm) / Time take for all tiles to fall (seconds)