Question

A sharp knife is more effective than a blunt knife. Why?

Answer 1

1. We know that pressure is inversely proportional to the area of the surface in contact.
2. pressure is given by $P=\frac{F}{A}$, where F is the force and A is Area.
3. A sharp knife has a smaller contact surface area and hence applies more pressure.
4. A sharp knife applies a greater pressure when used for cutting. This is why it cuts better.

Hence, a sharp knife has a smaller contact surface area and hence applies more pressure.