3 . When applied force = 0
Fa = 0 A = -fk/ m No motion occurs , the body stops
Relation between Coefficient of Static & Kinetic friction
fk = μk N
fs =< μs N
fs > fk ( to keep the body moving )
μs N > μk N Or , μk < μs Coefficient of kinetic friction is smaller than the coefficient of static friction .
Rolling friction o
o
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Rolling friction is applicable for bodies whose point of contact keeps changing
It is the force that opposes the motion of a body which is rolling over the surface of another
Bowling balls , rotating wheels are examples illustrating Rolling friction