David discovers the omnipresence and properties of air while contemplating a feather that floated to the ground. He learns that air fills spaces, weighs something, and exerts pressure in all ...
Feathers may have evolved on dinosaurs to frighten and flush out prey before they were used for flight, say researchers who built a winged robot and used it to scare grasshoppers. Pennaceous feathers, ...
Some results have been hidden because they may be inaccessible to you
Show inaccessible results