A block of mass 2 kg is kept on the floor. The coefficient of static friction is 0. 4. Let a force F of 2.5 N be applied on the block as shown in the figure, then what will be the frictional force between the block and the floor?

Friction always acts according to the requirement and tries to oppose relative motion (kinetic friction) or keeping a body at rest after application of force upto a certain range.We first calculate the limiting value of frictionfmax=μmg=0.4×2×9.8=7.84NIf this limiting value fmax≥Fext then block will not slip and static friction will be fs=Fext  but, if fmax≤Fext then the block will slip and friction will be equal to fmax.Since external forceFext=2.5N which is less than limiting value of friction.Hence, block will not slip.∴ Static friction on a bodyfs=Fext=2.5N