Can an egg fall better if dropped Sideway or ends first? The seemingly silly question has inspired a revolutionary leap by MIT researchers that upends the old classroom conventional wisdom and blows away pop-sci movies. Global conventional wisdom had dictated that eggs were strongest when head-first dropped, but new experiments introduce us to a jaw-dropping morsel: eggs are breathtakingly more resistant to dropping if dropped Sideway.
MIT’s egg drop competition, a year-round favorite among freshmen students of civil and environmental engineering, had until recently relied on the scientific literature which had supported vertical location as the location of shock absorption. But about three years ago, MIT associate professor Tal Cohen began to challenge that tradition. “We expected to confirm the vertical side was tougher based on what we had read online,” Cohen said, But when we looked at the data it was really unclear.
The mystery led Cohen’s research team to perform strict tests, such as dynamic drop tests and static compression tests. Static testing entailed loading incrementally to specify stiffness and toughness, while dynamic testing computed the probability of breaking on impact. To their surprise, both orientations required the same level of force to induce a crack. However, the largest difference was found to lie in the amount of compression the egg underwent prior to rupture. Horizontal eggs compressed more using the same amount of force applied and were more compliant. This compliance allowed horizontal eggs to absorb more energy and thus more resilient when undergoing drop tests.
This result refutes the hypothesis that eggs are more robust under axial loading. Dynamic drop tests confirmed the static results and established that equator-dropped eggs survived to greater heights before shattering than pole-dropped eggs. The experiments demonstrated that horizontally oriented eggs cracked only 5% of the time of 8 mm, while the vertically positioned eggs shattered 55%.
The structural difference between the orientations results in the difference in energy absorption capacity. The horizontally loaded eggs experienced ~30% greater displacement at cracking compared to the vertically loaded eggs. Eggs are therefore more difficult to load in the horizontal direction because they possess greater capacity to absorb energy prior to failure. The work highlights the importance of stiffness information over toughness information. As MIT’s Joseph Bonavia sums it up, “Stiffness is the amount of force you need to apply to deform an object, whereas toughness is the energy you can absorb before failure.”
The application extends beyond the egg drop experiment. The results provide insight into engineering situations, including how materials react to dynamic loading. Earthquake control systems and recoverable rockets are possibilities presented by the study, the research says. The research indicates earthquake control methods could be the direction that investigations of this type will take in the future. “My daughter had an egg-drop challenge this year, and I’m going to share this study with her teacher,” Cohen said.
The discovery is a note of warning that ancient science contains surprises if approached with gravity and good-humored openness to possibility. The discovery provides materials scientists, mechanical engineers, and science, technology, engineering, and mathematics educators a chance to revisit settled dogma in physics and seek new experimental strategies. The education is one of intellectual humility and awe, showing eggs placed on their side to be stronger than ever before imagined. As Cohen and her coauthors’ basic questions have illustrated, the finest insights all too frequently are those of the most basic question.
