To demonstrate this at an extreme, place a cone woofer face down on a rigid surface.
It is where three gigantic plates of the earth's rigid surface are converging.
The Young equation assumes a perfectly flat and rigid surface.
Quentin grabbed at it and touched a smooth, yet rigid surface undulating under his grasp.
A narrower water container and rigid surface would be the way to go.
The process uses a film of gelatine spread on a flat and rigid surface.
The substantial walls of large buildings were normally filled with loose matter between the more rigid surfaces.
The rat ran at the lower pane and bounced off its rigid surface.
Probably the only rigid surfaces are the meteor craters and mountain ranges.
Any time a rigid surface, such as asphalt, concrete or metal, needs to have a coating applied, the surface must first be prepared.