## Motion

Translation; Rotation; Rototranslation; Plane motion; Uniform motion; Uniform straight motion; Smoothly accelerated motion; Relative motion; Cyclical motion; Circular motion; Steady motion; Transient motion; Anharmonic motion.

## Force

The force may be thought of as an influence which tends to change the motion of an object. Forces are inherently vector quantities, requiring vector addition to combine them. The SI unit for force is the newton [N], which is defined by Newton = $$\dfrac{kg\cdot m}{s^2}$$ as may be seen from Newton’s second law. In mechanics, forces are seen as the causes […]

## Friction

Friction coefficient. Static friction. Kinetic or dynamic friction. Sliding friction. Rolling friction.

## Acceleration

To accelerate means to speed up. The greater the acceleration, the greater the change in velocity over a given time. The average acceleration is the rate at which velocity changes: $a_{avg}=\dfrac{\Delta v}{\Delta t}=\dfrac{v_f-v_0}{t_f-t_0}$ where $$v$$ is velocity, and $$t$$ is time. Acceleration is a vector in the same direction as the change in velocity, $$\Delta v$$. Since velocity […]

## Infrared

Infrared radiation. Infrared spectroscopy. Infrared astronomy.

Wind wave.

## Impedance

Acoustic impedance. Electrical impedance. How to calculate electrical impedance. Mechanical impedance. Wave impedance.

## Quantum spin liquid (QSL)

The quantum spin liquid is a state of matter that can be achieved in a system of interacting quantum spins. The word “liquid” refers to a disordered state in comparison to a ferromagnetic spin state (as much in the way liquid water is in a disordered state compared to crystalline ice). However, unlike other disordered states, a quantum spin […]

## Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term “laser” originated as an acronym for “light amplification by stimulated emission of radiation”. The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by […]

## Humidity

Humidity is the amount of water vapor in the air, measured as mass of water per unit volume or mass of air, or as a percentage of the maximum amount the air would support without condensation, or indirectly via the dew point. Saturation of the air occurs when the water vapor pressure reaches the vapor pressure […]