EXPLAIN WHY SLIDING FRICTION  IS LESS THAN STATIC FRICTION.

Dear Student
Static friction acts on a body at rest, i.e. when there is no relative motion between surfaces. In this condition the bodies are in equilibrium. As a matter of fact bodies at equilibrium take a finite time to get into motion. Also in static friction the frictional force mainly arises due to interlocking between the rough surfaces.

Sliding friction or kinetic friction acts between surfaces in relative motion. As the surfaces are already in motion, the inertia of motion plays a role to keep the surfaces in motion. Also here the interlocking between rough surfaces is low as the surfaces are in motion.

The above facts about static friction and sliding friction conclude that static friction is slightly larger than sliding friction. This is also proved in laboratory by performing various experiments.
Regards