In figure, the blocks are at rest and a force of 10 N acts on the block of 4kg mass. The coefficient of static friction and the coefficient of kinetic friction are ${\mathrm{\mu }}_{\mathrm{s}}=0.2$ and ${\mathrm{\mu }}_{\mathrm{k}}=0.15$ for both the surfaces in contact. The magnitude of friction force acting between the surface of contact between the 2 kg and 4 kg block in this situation is