Question

A block of mass 2 kg is placed on the floor . The coefficient of static friction between the two surfaces is 0.4. A horizontal force of 2.8 N is applied on the block parallel to the floor, what is the force of friction between the block and the floor? g=9.8m

Answer 1

the friction force maximum=0.4(2)(9.8)=7.84N.
the force acting on block is 2.8N.
but friction force can't exceed the applied force,if so the block will move in opposite direction of applied force.
so friction force is 2.8N or -2.8N with sign.