Why kinetic friction is always less than limiting friction

Dear Student,

The kinetic friction is usually not greater than the applied force. We start moving an object which increases the static force to prevent any motion. However, we keep applying more force until you reach a maximum value for the static friction. Then, the object begins to move.
Static friction is the friction that keeps an object in place. This friction must be overcome by energy to move the object. Because of a combination of surface irregularities and electrical charges between the object and the surface, the energy required to initially move the static object is greater than the energy required to keep it in motion. Because it takes more energy to move the static object, physicists say that static friction is greater than kinetic friction. The smoother the object and the smoother the surface the smaller the difference between the amount of static friction and the amount of kinetic friction.

Regards

  • -1
HI
​kinetic friction is always less than limiting friction as in kinetic friction the amount of energy produced by a moving body is much more than the energy generated by kinetic friction whereas limiting friction has a greater force as it is the energy that is stopping a body
from moving in the first place so the magnitude of the force is much greater.
hope you find this answer helpful
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One view is that when objects are stationary, the regions in contact (at the very very microscopic level), fuse together a little, forming little "cold welds". So while overcoming static friction one also had to overcome the cold welds. However, in bodies in motion, cold welds do not get time enough to form, so this requires lesser force. Hence Static Friction > Kinetic Friction
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