Why do sharp knives cut better due to pressure?

Sharp knives cut better due to pressure because a smaller surface area concentrates the force, increasing the pressure applied.

Pressure is defined as the force applied per unit area. In the case of a knife, the force you apply when cutting is distributed over the area of the knife's edge. The smaller the area (i.e., the sharper the knife), the greater the pressure that is exerted on the material being cut. This is why a sharp knife cuts better than a blunt one.

This principle can be explained using the formula for pressure: P = F/A, where P is pressure, F is force, and A is area. When the area A is small, as in the case of a sharp knife, a given force F will result in a larger pressure P. Conversely, if the area A is large, as in the case of a blunt knife, the same force F will result in a smaller pressure P. Therefore, a sharp knife, with its smaller surface area, will exert a greater pressure for a given force, making it more effective at cutting.

Furthermore, the increased pressure from a sharp knife allows it to penetrate more easily into the material being cut. This is because the material, under the influence of the high pressure, tends to move away from the area of contact, creating a path for the knife to move through. This is why you can cut through a tomato skin with a sharp knife with relative ease, but a blunt knife may just squash the tomato without cutting it.

In summary, the effectiveness of a sharp knife in cutting is due to the increased pressure it can exert on the material being cut, thanks to its smaller surface area. This principle of pressure is a fundamental concept in physics and is applicable in many other situations beyond just cutting with a knife.