How do sharp things cut?

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I’ve recently watched that video on the slingshot channel where he explains that a blade, even as sharp as a scalpel, cuts by friction, i.e. by moving it, or the thing being cut, “up and/or down” on its axis, meaning, and shown in the video, that if only pressure is applied perpendicular to the cutting edge, no cut shall be made.

Does that holds true for any kind of sharp-chutting mechanism?

I’ve tried helping a friend that was struggling with cuttint ribs by telling him to move the knife and not just aply pressure down, and was called stupid a because it was not a serrated knife. (Backstory for no reason whatsoever)

Of course with enough pressure on insufficient resistance i would assume anything “cuts”, like you can cut a cake with dental floss, but wouldn’t that be more akin to breaking?

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Anonymous 0 Comments

You don’t absolutely need to move the knife, and if you just kept putting pressure it would eventually work, but moving the knife absolutely helps. Even if there are no visible serrations, at the microscropic level the smooth blade of the knife looks more like a mountain range, with a lot of peaks and valleys, and as such it does work very much like a saw when you move it back and forth applying pressure.

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