Forces and Motion Vocabulary

Flashcards covering key vocabulary and concepts from the lecture notes on forces.

Force

A push or a pull exerted by one object on another object, which can change the object's speed, direction of motion, or both.

Newton (N)

The SI unit of force, equal to the force that gives a 1-kilogram object an acceleration of 1 m/s² (1 N = 1 kg·m/s²).

Dyne

A smaller unit of force, equal to the force that gives a 1-gram object an acceleration of 1 cm/s² (1 dyne = 1 g·cm/s²). Note: 1 N = 10³ dynes.

Fundamental Forces

The basic forces of nature resulting from the simplest interactions between objects, which cannot be divided into simpler forms. Includes the strong nuclear force, electromagnetic force, weak nuclear force, and gravitational force.

Strong Nuclear Force

The attractive force that holds protons and neutrons together in the nucleus of atoms.

Electromagnetic Force

The attractive or repulsive force between charged bodies, including both electric and magnetic forces.

Weak Nuclear Force

Plays a role in the radioactive decay of some nuclei.

Gravitational Force

The force of attraction between objects by virtue of their masses, responsible for the weights of bodies on Earth and the motion of planets.

Nonfundamental Forces (Derived Forces)

Forces that arise from the interactions brought about by the four fundamental forces, such as pushes, pulls, tension, and friction.

Contact Forces

Forces that result from direct physical contact between two objects, such as air resistance and friction.

Noncontact (Action-at-a-Distance) Forces

Forces that do not involve direct physical contact between objects; all fundamental forces are noncontact in nature.

Weight

The force that keeps an object attracted toward the center of Earth; related to mass by the equation w = mg (where g is the acceleration due to gravity).

Mass

The quantity of matter an object contains; its SI unit is the kilogram (kg). Mass is constant, whereas weight changes depending on the acceleration due to gravity.

Spring Balance/Force Sensor

Tools used to measure forces. Spring balances employ a spring inside a casing with a graduated scale; force sensors convert mechanical force into electrical signals.

Scalar Quantities

Quantities in physics that are entirely described by their magnitudes and appropriate units (e.g., mass, temperature, speed, time, energy, and distance).

Vector Quantities

Quantities that are completely described by their magnitudes, appropriate units, and directions (e.g., force, weight, displacement, and velocity).

Free-Body Diagram (FBD)

A diagram of forces acting on an object being analyzed, isolated from the rest of a system; forces are represented by arrows.