Using Your Finger Nails as a Screwdriver

Our nails are an isotropic, meaning the material has a different value when measured in different directions. This is much like wood, which is stronger along the grain. If you've ever tried to use your finger nails as a screwdriver, you've hit upon some of the design limitations,. But fortunately, at the same time, it's not so brittle that i just rip my nail to pieces when i'm trying and failing to do that.