1 …and they all fall Down! By: Natalie Jones Presented: 4/19/12

2 Glossary Slide 1: Title Slide 2: Glossary Slide 3: Question Slide 4: Hypothesis Slide 5: Materials Slide 6: Procedure Slide 7: Data- Trial 1 Slide 8: Data- Trial 2 Slide 9: Data- Trial 3 Slide 10: Results Slide 11: Graph Slide 12: Photograph Slide 13: Conclusion Slide 14: Discussion Slide 15: Works Cited (applications/research included) Slide 16: Works Cited cont’d (applications/research included) Slide 17: Acknowledgments

3 Question How does the distance between dominoes affect the speed at which they fall? Independent Variable: Distance between dominoes Dependant Variable: The speed (cm/s) of the chain Controlled Variables: Weight of dominoes, height/width of dominoes, length of chain, and surface underneath dominoes (friction).

4 Hypothesis It is my belief that the closer the dominoes are to each other, the faster the chain will be completed. I believe that this will occur because I think that the dominoes with less space in between them will pick up more momentum as they fall. Specifically, I think that the domino chain with 0.5 cm separating each domino will fall at the fastest speed.

5 Materials Dominoes (about 100) Stopwatch Ruler Masking tape Flat surface

6 Procedure 1. Lay 1 meter of masking tape down on a flat surface to use as a reference for how long the domino chains should be. 2. Line up the dominoes 0.5 cm apart from each other until they reach a distance of 1 meter. 3. Time how long it takes for the dominoes to fall. **Be sure to place yourself eye level with the chain of dominoes, as this is the easiest way to stop the timer exactly when the last domino falls. 4. Repeat steps 2-3 two more times for accuracy. 5. Repeat steps 2-4 with distances of 1.0 cm, 1.5 cm, 2.0 cm, 2.5 cm, and 3.0 cm between the dominoes. Make sure that each domino chain lines up to be a constant distance of 1 meter.

7 Data- Trial 1 Space between dominoes (cm) Time taken for the chain to be completed (sec) Speed (cm/s)

8 Data- Trial 2 Space between dominoes (cm) Time taken for the chain to be completed (sec) Speed (cm/s)

9 Data- Trial 3 Space between dominoes (cm) Time taken for the chain to be completed (sec) Speed (cm/s)

10 Results The data shows that speed and the distance between dominoes are inversely related; that is, speed increased as the spacing between dominoes decreased. The domino chain where the dominoes were 0.5 cm apart had the fastest speed.

11 Graph

12 Photograph

13 Conclusion My hypothesis was proven correct by my experiment. I believed that the domino chain with 0.5 cm separating each domino would fall at the fastest speed, and this prediction was supported by my data. It is my belief that the dominoes fell faster when they were closer together because more dominoes were able to fit into the meter- long chain, and the dominoes thus spent more time colliding with other dominoes, gathering force, than simply falling through air. This allowed the closer-spaced chains to gather more momentum than the farther-spaced chains, causing them to fall at a faster speed.

14 Discussion One problem I ran into during my project was how to accurately time the domino chains. At first, I would observe the chain from above and stop the timer when I heard the dominoes stop- relying mostly on my reflexes. However, this method produced scattered results, as that method wasn’t reliable. I then decided to move the domino chains onto my kitchen counter, where I could bend down and observe the falling chains at eye level. Looking at the dominoes from the side rather than from above made it a lot easier see exactly when the last domino fell, and I relied less on reflex and more on conscious decision to stop the timer. This method gave me reliable results that made sense mathematically.

15 Works Cited (applications/research included) All Experts. N.p., n.d. Web. 4 Jan This website suggests that the reason why it takes longer for domino chains with longer distances between each domino to fall is because it takes a larger amount of time for the dominoes to rotate in their arcs towards the next domino. I also came to this conclusion in my project. “The Domino Effect.” Exploratorium. N.p., n.d. Web. 4 Jan This website uses dominoes to model nerve cell transmissions. This helped me understand some possible applications of my project in the real world of science, such as the study of neurology. How Fast Do dominoes Fall?. University of Tennesse at Martin. N.p., n.d. Web. 4 Jan This essay details an experiment similar to my own, but it tests the effects of spacing upon the acceleration of a domino chain. I used the conclusions from this paper to design my own experiment to test the effects of spacing upon the speed of a domino chain.

16 Works Cited cont’d (applications/ research included) Larham, Ron. “Validation of a Model of the Domino Effect.” 19 Mar Arxiv. Web. 4 Jan This paper analyzes the current formula for determining the speed of a domino chain and comes to the conclusion that it is inaccurate, giving evidence that the formula has unaccounted-for limits. I used this paper’s formula to double-check my data, taking into account the variability of my experiment with a significance test. Leeuwen, J.M.J. Van. The Domino Effect. Leiden, The Netherlands: Instituut– Lorentz, Leiden University (UP), Lorentz, Leiden University. Web. 4 Jan This essay discusses the effects of friction upon the speed of a domino chain. This essay led me to understand that I had to control the friction of my domino chains, or else risk possible confounding of my results.

17 Acknowledgments Thanks to my amazing family for letting me use the kitchen counter for multiple hours during this project. Thanks to Mr. McClain for letting me borrow a calibrator. Thanks to the judges for allowing me to share my project.