Engineering Mechanics: Statics

Vocabulary flashcards covering the fundamental concepts, laws, and structural analysis methods from the Engineering Mechanics: Statics lecture.

Engineering Mechanics

A branch of physics that considers the action of forces on bodies or fluids that are at rest or in motion.

Statics

A subdivision of engineering mechanics that considers the effects and distribution of forces on rigid bodies which remain at rest.

Dynamics

A subdivision of engineering mechanics that considers the motion of rigid bodies caused by the forces acting on them.

Rigid Body

A defined amount of matter where the parts of which are fixed in position relative to each other; it is considered undeformable when the change in distance between any two points is negligible.

Force

The interaction that would change or would tend to change the state of motion of a body, characterized by magnitude, direction, and line of action.

Principle of Transmissibility

States that the external effect of a force on a body is the same for all points of application along its line of action.

Mass

The amount of matter, measured in $kg$ or $lbs$.

Weight

The pull of gravity toward the center of the earth, measured in $N$, $kg \cdot m/s^2$, or $lb \cdot ft/s^2$.

Concurrent Force System

A force system where all forces pass through a common point.

Parallel Force System

A force system in which the lines of action of the forces are parallel.

Coplanar Force System

A force system where the lines of action of all the forces lie in one plane.

Newton's First Law (Law of Inertia)

A particle originally at rest (or moving in a straight line with constant velocity) will remain at rest (or keep moving in a straight line in the same direction) unless acted upon by an unbalanced force.

Newton's Second Law (Law of Acceleration)

A particle acted upon by a force will accelerate in the direction of the force; the magnitude of acceleration is proportional to the magnitude of the force and inversely proportional to the mass ($F = ma$).

Newton's Third Law (Law of Interaction)

For every action, there is an equal and opposite reaction; the forces of interaction between two particles are equal in magnitude and oppositely directed along the same line of action.

Resultant

The single expression of the effect of a force system acting on a body, often computed as $R = \sqrt{R_x^2 + R_y^2}$.

Equilibrium

A state where a particle remains at rest or at a constant velocity, requiring the resultant force acting on it to be equal to zero.

Normal Force

A reaction force that is perpendicular to the surface at the point of contact when a body is in contact with a frictionless surface.

Roller Support

A support equivalent to a frictionless surface that can only exert a force perpendicular to the supporting surface.

Hinge Support / Pin Support

A support that reacts to translation of the body by producing vertical and horizontal reactions.

Fixed Support (Cantilever Support)

A support that prevents all motion (translation and rotation) by producing a maximum of three reactions.

Truss

A structure composed of members fastened in such a way as to resist change in its shape.

Method of Joints

A simplified truss analysis method that draws a free-body diagram at any joint, resulting in a concurrent force system using the first two equations of equilibrium.

Method of Sections

An analysis of a part of a truss containing two or more joints, generally involving a nonconcurrent, coplanar force system and the three equations of equilibrium.

Friction Force

A force component tangent to the surface that resists sliding.

Dry Friction

The friction force that exists between two unlubricated solid surfaces, subject to Coulomb's Theory.

Impending Sliding

The condition where surfaces are on the verge of sliding and the friction force reaches its maximum value ($f = f_{max} = \mu_s N$).