PITTSBURGH (KDKA) — Sometimes, science happens in an instant.
It can be too fast for our eyes and brains to process the tiny scientific details of what’s actually happening.
Thanks to slow-motion videography, we can take things that happen in a split second and see the physics behind our world play out. And this technology is built into many newer cell phones.
The levitating spring is a science project that perfectly captures this phenomenon.
All you need is a step stool or ladder, depending on how tall you are, and a slow-motion camera. You will also need a pre-tensioned spring, otherwise known as a slinky.
Dangle the spring and drop it while someone is recording your slow-motion video.
In real time, it doesn’t look like much is happening, but in slow motion, the bottom of the spring defies gravity.
It hovers until the top of the spring hits it. But why?
When the spring is stretched out and no longer bouncing, it’s at equilibrium. That is the point where the gravitational force downward is equal to the spring’s force upward.
That upward force is caused by the spring or the slinky trying to get back to its natural resting state, which is when the spring is all compressed together.
When you let go of the top of the spring, gravity takes over, and the top of the spring falls yet the bottom of the springs looks like it’s hovering in place since the top of the spring is still supporting the bottom.
The part of the spring that is stretched out is still at equilibrium, even though the top is falling.
So the spring’s force is still trying to carry it upward, while gravity is carrying the top part of the spring down.
This is going to happen until the spring collapses onto itself.