Author: Tru Physics
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Liouville’s Theorem
Introduction Liouville’s Theorem is a crucial principle in both statistical and Hamiltonian mechanics. Named after the French mathematician Joseph Liouville, the theorem asserts that the phase space volume occupied by a closed system remains constant throughout its evolution. Phase space, a key concept in physics, is an abstract space where all possible states of a…
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Ostwald Ripening
Introduction Ostwald Ripening is a phenomenon in physical chemistry named after the German chemist Friedrich Wilhelm Ostwald. It describes the process where smaller particles within a solution dissolve, and the material re-deposits onto larger particles. The process leads to the growth of large particles at the expense of small ones, which results in an increase…
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Albedo
Introduction Albedo is a fundamental concept in physics and earth sciences, denoting the reflectivity of a surface. Specifically, it is a dimensionless quantity indicating how well a surface reflects solar energy. Definition and Calculation Albedo is defined as the ratio of the radiation reflected to the radiation incident on a surface. The value of the…
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Rocket Propulsion
Introduction Rocket propulsion refers to the means by which rockets generate thrust to move forward. It is the fundamental principle that enables space travel. The principle that underpins rocket propulsion is Newton’s Third Law of Motion: for every action, there is an equal and opposite reaction. Basic Physics of Rocket Propulsion In rocket propulsion, a…
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Velocity Dispersion
Introduction Velocity dispersion refers to the statistical spread in velocities of particles in a system. It is a measure of how much the velocities of the particles deviate from the mean. The concept is widely used in physics and astronomy, especially in the study of galaxies and clusters of galaxies. Basic Understanding In a system…
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Centrifugal Force
Introduction Centrifugal force is often described as a ‘fictitious’ or ‘pseudo’ force because it does not arise due to a physical interaction between objects. It is a perceived force that acts on a body moving in a circular path, appearing to push it away from the center of the path. Basic Understanding The term ‘centrifugal…
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Maser
Introduction A maser is a device that produces coherent electromagnetic waves through amplification by stimulated emission. The term “maser” is an acronym for “Microwave Amplification by Stimulated Emission of Radiation”. Masers are the microwave-frequency precursor to the better-known laser (Light Amplification by Stimulated Emission of Radiation). Basic Working Principle The basic principle of a maser…
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Square-Integrable Functions
Introduction Square-integrable functions play a fundamental role in areas of physics such as quantum mechanics, signal processing, and optics. These are functions for which the integral of the square of the absolute value is finite. Definition A function defined over a measure space is said to be square-integrable if: This is commonly seen in the…
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Oberth Effect
Introduction The Oberth effect is a principle in astrodynamics and astronautics that states that the efficiency of a rocket’s propulsion system increases as the speed of the rocket increases. Named after the German scientist Hermann Oberth, who first described the effect, it is a fundamental principle used in mission planning and design for interplanetary travel.…
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Knudsen Number
Introduction The Knudsen number is a dimensionless number in fluid dynamics which describes the relative importance of molecular diffusion over molecular momentum transfer in a gas. It is named after the Danish physicist Martin Knudsen. Definition The Knudsen number is defined as the ratio of the molecular mean free path to a characteristic physical length…