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

If you look at a knife edge under magnification, you will see microscopic “teeth” on the edge of the blade. These teeth diminish the finer the grit the knife is sharpened at. A knife with a rougher finish will cut with a sawing action very well. If you polish it to a fine grit and remove these teeth, the knife will “push cut” better (meaning just pushing the blade through the material rather than sawing)