Consider what happens when you push both a pin and the blunt end of a pen against your skin with the same force. Decide what determines whether your skin is cut—the net force applied to it or the pressure.
We have to explain the observation difference between pin and blunt end of a pen against your skin with the same force. And also to explain which factor is responsible for skin cut - net force applied or pressure.
Step 1 of 3</p>
Pressure on the body is defined as the force applied per unit cross-sectional area of the body. Mathematically,
Step 2 of 3</p>
If net force is constant then,
This means that if the area is large, then the pressure is distributed over large area, and hence the effect is reduced and vice-versa.
The area of a blunt end of a pen is more than the tip of a pin, therefore the pin experiences more pressure than the pen tip.Thus, when the pin and blunt end of a pen is pressed against your skin with the same force, then it pricks the skin.