Question
Write the laws of friction.
✓
Answer
(1) Frictional force always opposes the movement
of the object, that is, it works in the opposite direction to the external force applied on the object.
(2) The value of limiting friction force doesn't depend on area of contact surfaces. It depend on nature of the surfaces of the objects.
(3) The maximum value $f_{s, \max }$ of static friction force is proportional to normal reaction (R).
i.e., $\quad f_{ s , \max } \propto R$
or $\quad f_{s, \max }=\mu_s R$
(iv) When the object starts sliding on the surface, the friction force reduces to kinetic friction force $f_{ K }$, where $f_{ K }=\mu_{ K } R$.
of the object, that is, it works in the opposite direction to the external force applied on the object.
(2) The value of limiting friction force doesn't depend on area of contact surfaces. It depend on nature of the surfaces of the objects.
(3) The maximum value $f_{s, \max }$ of static friction force is proportional to normal reaction (R).
i.e., $\quad f_{ s , \max } \propto R$
or $\quad f_{s, \max }=\mu_s R$
(iv) When the object starts sliding on the surface, the friction force reduces to kinetic friction force $f_{ K }$, where $f_{ K }=\mu_{ K } R$.
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