What are parts of them left behind?

When something moves and then stops, parts of it can stay where it was before.

Imagine you're riding your bike really fast down a path. You zoom past trees, flowers, and maybe even a friendly dog. Now imagine you suddenly stop, whoosh!, you’re still moving for just a little bit longer, right? Your body keeps going forward even though your feet have stopped pedaling.

That’s kind of like what happens when something moves and then stops. Think about a roller coaster that goes up a big hill and then zooms down the other side. When it reaches the bottom and suddenly stops, brake!, you feel like you're being pushed forward, even though the ride has stopped.

Sometimes, when things stop moving quickly, they leave little bits of themselves behind, just like your body keeps going for a second after you stop pedaling. These left-behind parts are like tiny echoes of motion. They help us understand how movement works in fun and exciting ways!