Why does the pin goes into the notice board but the finger doesnt?

The pin goes into the notice board because it is designed with a sharp point, allowing it to penetrate the material easily. In contrast, a finger is soft and lacks the necessary sharpness or rigidity to push through the board. Additionally, the pin's small surface area concentrates force on a smaller point, making it easier to pierce through, while the finger's larger area distributes force over a greater surface, preventing penetration.