Question

why does a sharp knife cut object more effectively than a blunt knife

Answer 1

Pressure is inversely proportional to area.
As sharp knife has less area so it applies more pressure as compared to blunt knife.

Answer 2

because the sharp knife occupy less area than the blunt knife that's why mostly a sharp thing are used to cut the thing . sharp thing take less particle while cutting an object so it is easier to cut cut the thing with sharper thing