This Material Gets Bigger When You Squish It

Summary by Krater

This video explains the physics behind dilatancy in sand and wet soil, demonstrating why sand appears to dry out when stepped on and how shear force causes its volume to increase.

From the video

Answers: Why does wet sand look drier when you step on it?

• Dilatancy in granular materials
• Sand behavior under shear force
• Volume changes in wet soil
• Physics of walking on wet sand

What it concludes

• Sand expands in volume when a shear force is applied because the particles shift and raise up, creating new gaps that pull water in from the surface.
• The dry area around a footprint on wet sand is a direct measure of the shear force applied to the sand.