Understanding Skateboard Pumping: Physics Explained

A team of engineers and mathematicians from ETH Zürich, along with researchers from The Institute of Statistical Mathematics and ATR Institute International in Japan, have successfully created a model to understand the physics of how skaters generate lift on a half-pipe by pumping their skateboards.

In their paper published in Physical Review Research, they explain their approach, which involved using the motion of a swing as a model to replicate the dynamics of skateboarding on a half-pipe. This analogy proved useful for understanding how skaters maneuver the ramp.

A half-pipe is a structure, usually made from wood or cement, resembling a pipe cut in half lengthwise. It forms a valley with two symmetrical slopes on either side. Skaters use the half-pipe to perform tricks, starting on one side, moving through the valley, and climbing the other slope.

The simplest action involves rolling down one side of the half-pipe, crossing the valley, and climbing up the opposite slope. At this point, skaters can either jump to the other side or roll back down. To maintain or increase their speed, skaters perform pumps—a technique where they adjust their body position to propel the skateboard forward. This is similar to the way children pump their legs to keep a swing moving. With sufficient speed, skaters can achieve airborne tricks by reaching the top of the ramp.

The research team began by examining existing physics models of swings and pendulums. They then reviewed videos of skateboarders to refine their model, incorporating elements specific to skateboarding, such as the skater's body movement and the angle of the board.

After developing the model, they explored the best pumping techniques theoretically. However, they noted that these techniques might not be practical in real-world scenarios as they could cause skaters to fly off the half-pipe. The researchers suggest that their model could be valuable for designing robots that need to maintain balance on uneven or sloped surfaces.