Question

A block of mass 2kg is placed on the floor.The coefficient of static friction between the two surfaces is 0.4 . A horizontal force of 2.5N is applied on the block . The force of friction between the block and the floor is ?

Answer 1

Force of friction= Coefficient of friction x Normal force on the surface
Here normal force on the surface is the weight of block = 2 x 10 = 20 N
So friction force = 0.4 x 20 = 8 N

8 N > 2.5 N
This means the object will not move. When the force applied on a body is less than the limiting frictional force then the frictional force will be equal to the applied force but in opposite direction.
So final frictional force will be 2.5 N in opposite direction.