The hypothesis was correct.
Coke: The objects covered by Coke were impacted by the corrosive effect of the phosphoric acid the beverage contains.
- Teeth: Badly discolored in just 24 hours. By Day 5, the tooth was much darker and the enamel was soft.
- Long nail: No change was apparent on Days 1-4. On Day 5, the surface of the nail was beginning to corrode.
- Short nail: The Coke definitely ate away part of the surface of the nail.
- Penny: The penny was very tarnished on Day 1. By Day 5 the penny was bright and shiny.
Sprite: Little change could be observed in the items objects covered by Coke.
Conclusion: This stuff really will rot your teeth out!