Question

How much force must be applied on a blade of length 4cm and thickness of 0.1mm to exert a pressure of 4000000pa?

Answer 1

The pressure by definition

$$P=\frac{F}{A}$$

Hence, the force applied on a blade

$$F=PA\\ =(4000000\:\rm Pa)\times(0.04\: m\times 0.0001\: m)=16\: N$$