Forces, Fundamental Interactions, and Free-Body Diagrams

Vocabulary terms and definitions covering dynamics, types of forces, the four fundamental forces of nature, electroweak unification, and free-body diagrams.

Dynamics

The branch of mechanics concerned with the forces that produce change in the motions of bodies.

Force

A push or pull that starts, stops, or changes the magnitude and direction of velocity of a body, transferring energy to that body.

Contact Force

A force exerted by one object on another directly at the point of contact, such as applied forces (pushes, pulls, twists) and friction.

Friction

The contact force that resists motion whenever the surface of one object comes into contact with the surface of another.

Electrostatic Force

A long-range force acting between charged objects, in which opposite charges attract each other and similar charges repel each other.

Magnetic Force

A non-contact force exerted by a magnet on other magnets and magnetic materials (such as iron, nickel, and cobalt), where like poles repel and unlike poles attract.

Fundamental Forces

The four primary forces in nature under which every other force is categorized: gravitational force, electromagnetic force, strong nuclear force, and weak nuclear force.

Gravitational Force

The weakest of the four fundamental forces; it is a long-range force that extends to infinite distance while progressively decreasing in strength.

Electromagnetic Force

A long-range fundamental force causing interactions between electrically charged particles, encompassing both electrostatic and magnetic forces, and operating within electromagnetic fields.

Strong Nuclear Force

A short-range fundamental force of the order of $10^{-14}\,\text{m}$ that holds atomic nuclei together by binding protons and neutrons, overcoming the repulsive electromagnetic force between positively charged protons.

Weak Nuclear Force

A short-range fundamental force of the order of $10^{-17}\,\text{m}$ responsible for nuclear disintegration and radioactive decay, such as $\beta$-decay where a neutron transforms into a proton, an electron ($\beta$-particle), and an antineutrino.

Electroweak Force

The theoretical unification of the weak nuclear force and electromagnetic force at high energy, formulated by Dr. Abdus Salam, Sheldon Glashow, and Steven Weinberg, who shared the 1979 Nobel Prize in Physics.

Free-Body Diagram

A special type of vector diagram used to show the relative magnitudes and directions of all external forces acting on an object in a given situation, typically represented by a box with force arrows pointing outward from its center.