Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
Force of friction arises due to interlocking of irregularities on the 2 surfaces in contact. When a heavy item is located at the ground, the interlocking of irregularities at the surfaces of field and ground turn out to be strong. This is due to the fact the 2 surfaces in contact are pressed harder. Hence, extra pressure is needed to triumph over the interlocking. Thus, to push the heavier field, Seema has to apply a more pressure than Iqbal.
