Question

A sharp knife cuts better than a blunt knife. Which of the following options gives the correct reason for this?

• A. A sharp knife is heavier than a blunt knife.
• B. Sharp knives are usually made of silver which has more strength.
• C. A sharp knife has a smaller contact surface and hence applies more pressure.
• D. A sharp knife has more surface area and hence applies more pressure.

Answer 1

The correct option is C A sharp knife has a smaller contact surface and hence applies more pressure.

Pressure is the ratio of thrust and area on which it acts.
$Pressure=\frac{\text{Force}}{\text{Area}}$

A sharp knife has a lesser surface area at its edge than a blunt one. So, a sharp knife applies a greater pressure for the same amount of force. Hence, sharp knife cuts better than a blunt knife.