This page offers a collection of physical constants and unit conversions across various categories, including density, energy, force, length, mass, power, stress, and toughness. It provides equivalenc...This page offers a collection of physical constants and unit conversions across various categories, including density, energy, force, length, mass, power, stress, and toughness. It provides equivalences between units, such as the conversion of 1 Mg/m³ to 1 gm/cm³ and of 1 J to calories and Btu. The page also lists fundamental physical constants like the Boltzmann constant, gas constant, Avogadro constant, and gravitational acceleration.