Magnetic Newton’s cradle

The question

Which factors affect the behaviour of a magnetic Newton’s cradle? We changed one thing at a time. In the order we tested them, from most to least thoroughly:

1. the angle the first magnet is released from
2. the number of magnets (three or five)
3. the separation between magnets at equilibrium
4. friction between the wires and the frame
5. the strength of the magnets
6. the mass of each magnet

Why it’s interesting

In an ordinary Newton’s cradle, one ball in means one ball out. With magnets the balls push on each other before they touch, so that “one in, one out” behaviour is no longer guaranteed, and how energy and momentum pass along the line stops being simple.

What we built

Magnetic cradles are rare and we couldn’t source one, so we built our own from scratch and put tracking stickers on each magnet.

How you made it (frame, how the magnets hang, the stickers), with two or three build photos.

Method

We filmed every run in slow motion. Motion-tracking software then turned the footage into the position of each marker against time, and from that, velocity.

We used Tracker, a free video-analysis tool, and did two runs for each parameter.

Results

At least two plots with labelled axes and a sentence under each, plus one short clip with the markers visible. Optionally the tracking data as a CSV download.

What we found

Plain-language conclusions with caveats. Release angle and the number of magnets were tested most, so they carry the strongest claims; say that the magnet strength and mass results are only indicative.

What went wrong, and what I’d do next

An honest paragraph or two. Reviewers value this more than clean results.

My role

This was an in-school IYPT project in Year 11, in a team of three. It was the in-school stage, not the national competition. I did the motion tracking and the data processing.

What I took from it

One sentence.