The Slinky has long been a popular toy for children and adults alike. The concept is simple: you pull the top end of the Slinky down, causing it to “walk” down stairs, flipping when it reaches the step below. For many people, this makes no sense because they never learned about springs in school! This post aims to clear up that confusion by explaining how a Slinky walks down stairs.
When you pull the top of a Slinky down, it causes the coils at the bottom to stretch out. The further you pull, the more they stretch. At some point, the coils will be so stretched that they will snap back into place. This creates a force that propels the Slinky downwards. As it moves down, new coils get pulled down and stretch out, jumping over the ones that snapped back. This continues until all of them have been used up or you stop pulling on it.
In order to create a force that propels the Slinky downwards, we need one more idea from physics: how forces work in depth changing situations (e.g., when the Slinky is stretched out and when it’s not). When you pull on a Slinky, some of the potential energy stored in its springiness gets transformed into kinetic (motion) energy. The longer the chain becomes, the more force there will be pushing downwards to get it moving again. If we pulled hard enough for long enough, eventually all of the potential energy would be turned into kinetic, and the Slinky would fly down the stairs!
So there you have it: that’s how a Slinky walks down stairs. It’s all thanks to physics! Now go impress your friends with your newfound knowledge