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How are statics, kinematics, and dynamics different in mechanics?

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A diagram with labeled vector illustrations. Panel A shows vector addition with two green arrows A and B forming a parallelogram, and their sum C as a red diagonal. Panel B shows vector subtraction, with A and negative B forming resultant D. Panel C demonstrates vector components using angles and projections. Panel D uses the right-hand rule with thumbs to show the direction of the cross product E = A x B and its opposite, -E = B x A. — mechanics Figure 1: (A) The vector sum C = A + B = B + A. (B) The vector difference A + (−B) = A − B = D. (C, left) A cos θ is the component of A along B and (right) B cos θ is the component of B along A. (D, left) The right-hand rule used to find the direction of E = A × B and (right) the right-hand rule used to find the direction of −E = B × A.

In classical mechanics, the study of objects is categorized based on their state of motion and the influence of forces. These branches are distinguished as follows:

Kinematics: This branch provides a geometric description of motion—such as position, velocity, and acceleration—without considering the forces or masses that cause the motion.123
Dynamics: This field focuses on the motion of objects in relation to the physical factors that affect them, including force, mass, momentum, and energy. Some authors include kinematics as a subset of dynamics.31
Statics: This subdivision concerns bodies at rest under equilibrium conditions, where the sum of all forces and torques acting on the body is zero. It is often treated as a special case of dynamics.145

While kinematics describes how an object moves, dynamics explains why it moves by analyzing the forces involved. Statics serves as the analytical framework for ensuring structures remain stable and stationary.43