Experiment with Marbles. Invisible Forces in Motion

🎂 5 + years ⏱️ 20 min 📍 Everywhere ⭐ very easy

Have you ever wondered what happens when a marble rolls into a line of other marbles? Do they all bounce around? Do they stop? Or does just one move? With this experiment, you’ll find out! You’ll create a simple track for your marbles and observe how the movement transfers through the line. When you give one marble a push, it doesn’t just stay still; it passes on its energy. Each marble in the line feels the push and passes it to the next one. But only the last marble rolls away. This is physics that you can see right before your eyes! You can test how the experiment changes when you use more or fewer marbles or change their spacing. Have fun exploring and discovering the secret forces!

What you'll need

1 sheet of A4 paper
Or two rulers
5 or more marbles

How it works

Take the A4 sheet and fold it lengthwise in half. Then fold the open edges back to the crease to create a sort of trough where marbles can sit.
Place four marbles in the paper fold so that they touch each other. Make sure they are well aligned so they can transfer energy directly.
Set a fifth marble a little distance in front of the line of four marbles. Give this marble a gentle push so it hits the first marble in the line.
Watch closely what happens when the fifth marble hits the first one. Almost all the marbles stay in place, but the last marble is pushed away by the transferred energy and rolls off.
What happens if you push two marbles at the same time? Try the experiment with different numbers of marbles or give the first marble a stronger or weaker push. Observe how the results change.
Why is that? The force you give with your finger doesn’t disappear. It travels from marble to marble, but each one stays almost in place. Only the last marble has no one in front of it to pass the force to, so it rolls forward.
But if you push two or three marbles against the line at the same time, then double or triple the energy travels through the line. This means that as many marbles roll away at the end as you pushed at the beginning.