“Et tu, Brute force?” Scissors asked.

Force. Mechanical advantage. Friction. And how scissors cut through food as a lever.


scissors class-1 lever 1-Minute NomNom

Hail scissors! Like knives, scissors have become an important part of the kitchen for cutting foods.

Force/Effort is applied via the handles.  The little rivet-like knob in the middle where the handles and blades join acts as the fulcrum. A force is then produced at the blades for cutting and shearing foods.scissors class-1 leverSuch an arrangement of force applied fulcrum and force produced at the load makes the scissors a class-1 lever. In fact because the scissors comprises two handles and two blades, a pair of scissors is actually two class-1 levers. Class-1 levers multiplies effort because they…

“… provide mechanical advantage. This means that they allow you to move a large output load with a small effort.” (Source: BBC)

scissors class-1 lever
Like any lever, the scissors’ class-1 lever is governed by the equation:

(Force applied at handle) x (distance from fulcrum) =
(Force produced at blades) x (distance from fulcrum)

This means if we place a piece of food at a point along the blades that is closer to the fulcrum than the distance of the handles (where we apply the force) to the fulcrum, the greater the force that will be produced on the food.KnivesLike knives, this force at the blades first makes a split in the food surface through friction.  As more force is applied, the blades slice through the food fairly easily (find out more about how blades and knives slice through food in the 1-Minute NomNom “Slice slice baby!“)

If the blades are thin — especially when they are sharp — the force we apply is concentrated into a much smaller area. The pressure that results is greater (since Pressure = Force ÷ Area), translating into a greater cutting force at the blades.

scissors class 1 leverSo there you have it. The scissors is a big part of the kitchen, not through brute force alone, but also through the science of levers, pressure and friction.


Screen Shot 2015-01-10 at 6.02.39 pm

Like this? You don’t need brute force to like me to discover more. All you need is a minute a day to explore the world’s marvels through the phenomenon of food!

photos: in order – depositiphotos/grzymkiewiczkeeratifiamolisibiryankagrzymkiewicz

Leave a Reply