Question

it is difficult to cut using a pair of scisdor with blunt blades explan

Answer 1

It is difficult to cut using a pair of scissors with blunt blades because the blunt blades have larger surface area , so the force applied on them will be greater  and on other side , if we use the sharp blades the force we will apply would be less and with small amount of force the thing can be cut easily .

The larger the surface area the force acting on a particular pt. is Less and vice - versa.

Answer 2

A paper will be cut if we apply the required pressure on it. 
We know that if we apply a certain amount of force on a smaller area, the pressure applied will be more.
A scissor with blunt ends will have more surface area than a scissor with sharp edges. In a scissor with sharp edges, we will have to apply less force than in a scissor with blunt edges. So it is difficult to cut with blunt scissor than a sharp edged scissor.