Question

Fig. shows two boys applying force on a box. If the magnitude of the force applied by each is equal, will the box experience any force of friction?

Fig. 12.3 

Answer 1

Frictional Force

1. When two surfaces contact and slide against each other, then a force is generated which is termed frictional force.
2. The frictional force is directly proportional to the roughness of the surface. The more rough surface will the more frictional force will be generated.

Force experienced by the box due to friction

1. The net force will be zero, as both the boys are applying the same magnitude of the force.
2. Let's assume the left-hand side boy is applying a force $F$ in the right direction whereas the right-hand side boy is applying a force $F$ in the left direction. As the magnitude of both the F is the same. But the direction of force applied is the opposite.
3. Therefore the force get's canceled out from both ends.
4. The box will experience no frictional force.

The box will experience no force of friction.