Assertion (A): The coefficient of kinetic friction is always strictly less than the coefficient of limiting static friction. Reason (R): Once motion starts, the inertia of rest is broken and interlocking of surface irregularities is less effective.
A. Both A and R are true but R is NOT the correct explanation of A.
B. A is true but R is false.
C. Both A and R are true and R is the correct explanation of A.
D. A is false but R is true.
Answer: Option C
Solution (By JKSSB Mock Tests)
Static friction opposes impending motion, reaching a maximum called limiting friction. Once the object moves, it doesn't have enough time for the microscopic irregularities (asperities) of the two surfaces to interlock strongly. Thus, the force required to keep it moving (kinetic friction) is slightly less than the force required to start the motion.
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