Free · Physics play

Stack and Smash Physics Lab

Build a block tower, then drop a heavy ball and watch every bump and tumble.

  • Clear, kid-friendly steps
  • Private in your browser
  • No signup

Physics play lab

Change one thing and watch

Tap anywhere in the lab to drop a shape. Everything stays on this page.

0 moving objects

Live experiment

Stack & Smash

Powered by Matter.js, an open-source library available under MIT.

Three simple steps

How to use it

  1. Pick a shape, gravity, or bounce level.
  2. Tap the play area or press the big button to add an object.
  3. Watch what happens, then reset the lab and try a new idea.

Private by default

Your words and choices stay in this browser tab. There are no accounts, uploads, ads, or trackers inside the tool. Close the tab and the working data is gone.