Question

why are the tips and edges of cutting and piercing tools made sharp

Answer 1

because of the surface area we want to reduce because we have to increase the pressure so that food or anything whatever we want to cut Get cut easily

Answer 2

The cutting edges of tools like blades, knives etc., are provided with sharp edges to cut the things easily as the sharp edges has small area on which the force is applied, hence more pressure is applied.
we know Pressure = Force/Area
Hence we can say that pressure is inversely proportional to area that means this area will be equals to more pressure and more area will be equals to less pressure
the pressure exerted on a small surface area is more than the pressure exerted on the large surface area
From that we can conclude that equal force can exert higher pressure on a small area. This is why the cutting edges of tools like blades, knives etc., are provided with sharp edges to cut the things easily becausehigh pressure at the end of these sharp surfaces can easily pierce through wooden, plastic etc., surfaces.