F≤μR, where F is frictional force, μ is the coefficient of friction, and R is the normal reaction force.
What is friction in mechanics?
Friction is a **force** that opposes the **relative motion** between two surfaces in contact.
Friction rules
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Three possible scenarios with F≤μR
P≤μR then F=P, equilibrium
P=μR then F=μR (MAX VALUE), object is in limiting equilibrium, i.e about to sleep
If P>μR then F=μR, the object will move in the direction of P>F (friction is at it's max value and can no longer match applied force,P to prevent motion.)
What is it when friction acts on a stationary object?
Static friction-it is equal but opposite to force applied to try and move the object.
