In nursery school, I began to wonder about the problem of inertia. Not in those terms, of course. But I considered the problem of a tricycle, at speed, colliding with the wooden edge of the sandbox. I understood that the tricycle would stop immediately, but what about its rider? It seemed implausible that I, too, would simply stop, yet I couldn’t keep going either. What would happen?
I decided to do an experiment. Taking one of those heavy, blue-painted metal tricycles we had then and lining it up at the far end of the playground, I waited until there was a clear line of blacktop to the sandbox. Then I pushed off, not sitting on the tricycle, but using the footpad in the back while leaning into the handlebars for maximum speed.
The experiment was, in its way, a success. I learned that the tricycle does indeed stop more or less immediately, while the rider keeps going: over the handlebars, in this instance, and face-first into the hard, gritty wheel, before toppling into the sand and then not being able to whistle — a skill I had only recently acquired — until the swelling went down and the scabs healed.