Why does a knife need to be pulled back and forth to cut things?

Question

Like what difference does the cutting motion do compared to just pushing down a knife ?

In: Physics

Answer 1

Depending on the material you cut and the sharpness of the knife, sawing may not be necessary, but it’s usually helpful for the following reasons:

1. Sharpness of the knife: if the knife isn’t sharp, the imperfections in the edge turn it into a saw when you use sawing action, helping with the cut.

2. Debris accumulation: as you cut, some food gets stuck to the edge and prevent effective cutting as you go deeper. Sawing action moves this debris away and gets an effective cut

3. Fiber stretching: Sawing action exposes new to-cut areas and stretches the fibers of the item being cut, making it easier to cut