Can you build a car that travels farther than you push it? [Tom Stanton] shows us that you can, using a capacitor and some nifty design tricks.

[Tom]’s video shows us the construction of a small 3D printed trike with a curious drivetrain. There’s a simple generator on board, which charges a capacitor when the trike is pushed along the ground. When the trike is let go, however, this generator instead acts as a motor, using energy stored in the capacitor to drive the trike further.

When put to the test by [Tom], both a freewheeling car and the capacitor car are pushed up to a set speed. But the capacitor car goes farther. The trick is simple – the capacitor car can go further because it has more energy. But how?

It’s all because more work is being done to push the capacitor car up to speed. It stores energy in the capacitor while it’s being accelerated by the human pushing it. In contrast, after being pushed, the freewheeling car merely coasts to a stop as it loses kinetic energy. However, the capacitor car has similar kinetic energy plus the energy stored in its capacitor, which it can use to run its motor.

It’s a neat exploration of some basic physics, and useful learning if you’ve ever wondered about the prospects of perpetual motion machines.