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Mechanical calculator
A mechanical calculator, or calculating machine, performs arithmetic using gears and drums rather than electronics; first built in 1623, it was displaced by electronic calculators in the 1960s.
Mechanical cloaking
Mechanical cloaking is the design of a coating or structure that makes a defect in a material undetectable in its elastic response, as if it were not there.
Mechanical energy
Mechanical energy is the sum of a system's kinetic and potential energies, measured in joules; friction converts it into thermal energy, but it is conserved otherwise.
Mechanical equilibrium
Mechanical equilibrium is the state of a rigid body in which linear and angular acceleration are zero, so it moves at constant velocity or stays at rest.
Mechanical equivalent of heat
The mechanical equivalent of heat, or Joule's equivalent, is the number of units of mechanical work equivalent to one unit of heat, determined by James Prescott Joule's paddle-wheel experiments of the 1840s.
Mechanical explanations of gravitation
Mechanical explanations of gravitation are superseded physical theories explaining gravity through contact mechanisms, chiefly the vortex theories of Descartes and Huygens and Le Sage's pushing corpuscles.
Mechanical impedance
Mechanical impedance is the frequency-dependent ratio of applied sinusoidal force to vibration velocity at a point in a mechanical system, the mechanical counterpart of electrical impedance in AC circuit theory.
Mechanical memory in disordered solids
Mechanical memory in disordered solids is the ability of amorphous solids, such as sheared glasses, to store readable memories of past strain amplitudes under cyclic deformation.
Mechanical metamaterials with negative dynamic mass density
Mechanical metamaterials with negative dynamic mass density are engineered composites whose effective mass density turns negative near local resonances even though every constituent has positive mass.
Mechanical resonance
Mechanical resonance is the large-amplitude response of a mechanical system driven by a periodic force at or near one of its natural frequencies, building until damped and supplied power balance.
Mechanical spectroscopy
Mechanical spectroscopy is a family of characterization techniques that applies oscillatory stress or strain to a material and measures the phase-shifted response, yielding storage and loss moduli.
Mechanical unfeelability cloak
A mechanical unfeelability cloak is a metamaterial coating that makes an embedded object elastically undetectable by touch, first demonstrated at the Karlsruhe Institute of Technology in 2014.
Mechanical watch
A mechanical watch, also known as a mechanical wristwatch, is a watch driven by a wound mainspring and regulated by a balance wheel, with no battery.
Mechanical wave
A mechanical wave is a disturbance that travels through a medium such as air, water, or rock, carrying energy; sound, water, and seismic waves are examples.
Mechanically axially chiral rotaxanes
Mechanically axially chiral rotaxanes are mechanically interlocked molecules in which the bond between a macrocycle and a stoppered axle is the sole stereogenic element, identified by Goldup in 2022.
Mechanically interlocked crystals
Mechanically interlocked crystals are crystalline materials whose integrity comes from mechanical bonds, topological entanglements that cannot be separated without breaking a covalent bond, including 2025's 2D interlocked polymers.
Mechanically interlocked molecular architectures
Mechanically interlocked molecular architectures are chemical structures whose components are threaded or linked through one another, unable to separate without breaking a covalent or coordinate bond.
Mechanically planar chirality
Mechanically planar chirality is a form of molecular chirality in which the mechanical bond of an interlocked molecule, typically a rotaxane, is the stereogenic element rather than any covalent feature.
Mechanics
Mechanics, also known as theoretical mechanics, is the branch of physics that studies the motion of objects and the forces causing it, divided into kinematics and dynamics.
Mechanistic models
A mechanistic model is a scientific model representing a phenomenon through the organized parts, activities, and interactions of the mechanism that produces it, central to philosophy of science since the 1990s.
Mechanobiology
Mechanobiology is the study of how force, geometry, and matrix elasticity define cell and tissue function, converting mechanical stimuli into chemical responses via mechanotransduction.
Mechanocatalysis
Mechanocatalysis is a subfield of mechanochemistry in which mechanical energy from milling, grinding, or shearing drives catalytic reactions, enabling solvent-free processes such as cellulose depolymerization.
Mechanochemical activation
Mechanochemical activation is the use of mechanical energy, most often from ball milling or grinding, to induce chemical reactions or structural changes in solids, with applications in synthesis, pharmaceuticals, and recycling.
Mechanochemical cross-coupling
Mechanochemical cross-coupling performs transition-metal-catalyzed carbon–carbon and carbon–heteroatom bond-forming reactions, including Suzuki–Miyaura and Sonogashira couplings, in ball mills, generally without bulk solvent, to reduce solvent waste.
Mechanochemical depolymerization
Mechanochemical depolymerization breaks polymer chains into monomers or small molecules using mechanical force, typically ball milling, rather than heat or bulk solvents, enabling solvent-free chemical recycling of plastics.
Mechanochemical polymer degradation
Mechanochemical polymer degradation cleaves polymer chains using mechanical force from techniques such as ball milling and ultrasonication, a solvent-free form of chemical recycling that turns waste plastics back into monomers.
Mechanochemical synthesis
Mechanochemical synthesis carries out chemical reactions by direct absorption of mechanical energy, most commonly in a ball mill, without a bulk solvent, spanning organic, pharmaceutical, and materials chemistry.
Mechanochemical synthesis by twin-screw extrusion
Mechanochemical synthesis by twin-screw extrusion (TSE) is the continuous, solvent-free counterpart to batch ball milling, first reported for molecular synthesis in 2015 and used for metal-organic frameworks and pharmaceuticals.
Mechanochemical unzipping of polyladderene to semiconducting polyacetylene
Mechanochemical unzipping of polyladderene to semiconducting polyacetylene is a polymer mechanochemistry transformation reported by a Stanford team in 2017, in which mechanical force unzips insulating polyladderene into conjugated polyacetylene that turns deeply colored and semiconducting.
Mechanochemistry
Mechanochemistry is the branch of chemistry in which reactions are induced by mechanical energy such as grinding or milling, a solvent-free approach aligned with green chemistry.