Dynamics and Types of Forces

Vocabulary flashcards covering introductory dynamics concepts, force measurement instruments, force diagrams, contact and non-contact forces, and gravitational calculations.

Dynamics

The study of the causes of motion, explaining why objects move the way they do based on the forces acting on them.

Force

A push or a pull exerted on an object; it has direction, making it a vector quantity.

Newton ($\text{N}$)

The derived SI unit of force named after Isaac Newton, equal to $1\,\text{kg}\cdot\text{m/s}^2$.

System diagram

A simple sketch of all objects involved in a situation used to determine which objects push or pull on other objects.

Free-body diagram (FBD)

A simple drawing representing an object being analyzed (as a rectangle or large dot) and all external forces acting on it drawn as arrows pointing away from the center.

Applied force ($F_a$)

A contact force that results when one object comes into contact with another object and either pushes or pulls on it.

Tension ($F_T$)

A pulling force exerted on an object by a rope or string that always points toward the rope or string.

Normal force ($F_N$)

A perpendicular force exerted by a surface on an object in contact with it, always directed as a push pointing away from the surface.

Friction ($F_f$)

A force that opposes the sliding of two surfaces across one another and resists the motion or attempted motion of an object, acting parallel to the surface.

Contact forces

Forces that require physical contact between two objects to act, such as applied forces, tension, normal force, and friction.

Action-at-a-distance forces

Forces that do not require physical contact between objects to exert an effect, also known as non-contact forces.

Force of gravity ($F_g$)

An action-at-a-distance force of attraction between any two objects due to their mass; at Earth's surface, it always points down toward Earth's centre and is calculated as $F_g = mg$.

Acceleration due to gravity ($g$)

The constant acceleration experienced by objects close to Earth's surface, equal to $9.8\,\text{m/s}^2\text{ [down]}$.

External force

A force exerted on an object caused by another object pushing or pulling on it.

Internal force

A force that occurs when an object exerts a force on itself.