To show that the increase in weight will increase the static friction between two surfaces.
Friction is the force exerted by the surface when the object moves across it. Force of friction is opposite to the direction of motion.
Consider a book is on the table. When we zoom the interface of surfaces of book and table there are a lot of irregularities between the surfaces of table and book. Irregularities of two surfaces interlock into each other. We want to apply force to overcome the interlocking of irregularities.
As roughness of surface increases, number of irregularities increases. The force of friction increases.
Static friction is the force of friction which opposes the applied force when object is at rest. Force required to overcome friction at an instant an object moving from rest is measure of static friction.
Sliding friction opposes the moving of an object.
The force required to move to book alone is lesser than force required to move book if we put some weights on the book. As weight on the book increases the force of friction increases.
