Science: An Investigative Look At How A Lawnmower Cuts Grass

July 6, 2018

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This is a ten minute video of Destin from Smarter Every Day discussing how a lawnmower is able to cut something as easily bendable as grass, with such a relatively dull metal blade (albeit spinning incredibly fast). I think I learned something. Maybe? "Have you ever?" Only how not to learn from mistakes.

A lawnmower blade is different [than scissors]...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

So how does a lawnmower cut grass? SPOILER: The bent tabs on the ends of a lawnmower's blades actually create lift on the grass, so they're being pulled upwards (like a barber pulling your hair taught) while they're cut below. Science! Of course if you asked my dad how lawnmowers work he'd tell you it's by yelling at me enough to finally go push it around the yard.

Keep going for the video while I go cut the grass in flip-flops until my mom comes out and yells at me, hopefully with some lemon-lime Gatorade.

Thanks to Dweez, who agrees there's nothing more refreshing than a dip in a neighbor's pool after cutting the grass. "HEY -- GET OUT OF THERE." Gotta go!

  • Jenness

    it's amazing the things that took thousands of attempts, decades or even centuries to perfect for us to go "meh" about them now and just take them for granted.

  • GeneralDisorder

    I find it interesting that he never thought about the airflow thing when he was making the first slow-mo videos. Every lawnmower throws the clippings.

    Anyway, this is a great video.

  • TheQiwiMan

    Destin is such a freakin stud. He’s physically incapable of making a video that’s not interesting.

  • Bling Nye

    ...hook the Flowbee to the Kirby...

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