# Physics 112 Ch4 Review

## Terms

copy deck
Inertia -
The reluctance of an object to change its state of motion.
Equilibrium -
The state of a body or physical system at rest or in unaccelerated motion in which the resultant of all forces acting on it is zero.
Newtonâ€™s first law â€“
an object at rest will remain at rest, and an object in motion with constant speed will remain at constant speed unless acted on by an external unbalanced force (if ΣF = 0, then V = Constant).
Newtonâ€™s third law â€“
every action must produce an equal but oppositely directed reaction (F on A by B = -F on B by A).
Normal force â€“
a force that is perpendicular to the surface plane.
Friction force -
A force that resists the relative motion or tendency to such motion of two bodies in contact.
Equilibrant â€“
a force equal in magnitude to the resultant force but opposite in direction.
Reaction force -
An equal and opposite force exerted by a body against a force acting upon it.
Coefficient of friction â€“
ratio of the amount of friction by the surface and the normal force exerted by the force (μ f = Ff / N).
Static Friction â€“
A force that exist between two surfaces while motion is impending.
Kinetic Friction â€“
the frictional force between to surfaces while and object is moving.
Free body diagram â€“
A vector diagram which describes all forces acting in a particular body or object.

12