How Lawn Mower Blades Cut Grass

While performing outdoor household chores, engineer Destin Sandlin of Smarter Every Day decided to have a look at the physics and engineering behind lawnmowers and how exactly they cut grass. What he discovered is that rather than relying on “localized shear” from items with opposing blades (i.e. scissors and hair clippers), the mower has a single long swinging blade that uses inertia to perform its single purpose of clearing grass.

A lawnmower blade is different …there’s no opposing blades it’s like an open-ended system …a massive blade with a lot of inertia and it swings along really fast and it hits the grass but the grass is so lightweight it kind of just moves out of the way