Physics 101: Mechanics

Mechanics

The branch of physics dealing with the motion of objects and the forces that cause or change that motion.

Newton's First Law (Inertia)

An object at rest stays at rest, and an object in motion stays in motion at constant velocity, unless acted upon by a net external force.

Newton's Second Law

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma).

Newton's Third Law

For every action, there is an equal and opposite reaction. When object A exerts a force on object B, object B exerts an equal but opposite force on object A.

Force

A push or pull on an object that can cause it to accelerate, decelerate, or change direction. Measured in newtons (N).

Mass

A measure of the amount of matter in an object, expressed in kilograms (kg). It resists acceleration and is independent of gravity.

Weight

The force of gravity acting on an object's mass, equal to mass times gravitational acceleration (W = mg). Measured in newtons.

Velocity

A vector quantity describing the rate of change of an object's position, including both speed and direction. Measured in meters per second (m/s).

Acceleration

The rate of change of velocity over time, measured in meters per second squared (m/s^2).

Friction

A resistive force that opposes the relative motion or tendency of motion between two surfaces in contact.