Convert Pound-force Square Second/Foot (lbf·s²/ft) to Femtogram (fg) instantly.
About these units
Pound-force Square Second/Foot (lbf·s²/ft)
This unit is part of the British Gravitational System, where mass is defined from force rather than the other way around. It can be interpreted as an inertial mass unit, since applying 1 pound-force to it would produce an acceleration of 1 foot per second squared. Historically, before the SI system clarified the distinction between force and mass, engineering fields often used mixed systems where pounds could represent either force (lbf) or mass (lbm). The unit lbf·s²/ft was introduced to straighten out these ambiguities in dynamic calculations such as impact forces, mechanical oscillations, and safety load computations. Today, the unit survives mostly in engineering textbooks, legacy calculations, and historical documentation. It demonstrates how complex and inconsistent measurement systems once were, and why global scientific communities moved toward SI clarity.
Femtogram (fg)
A femtogram is 10⁻¹⁵ grams, an extraordinarily small unit used primarily in molecular biology, analytical chemistry, and particle science. At this scale, masses correspond to small clusters of molecules, fragments of genetic material, or trace contaminants in environmental samples. In genomics, for example, the femtogram level may represent the mass of DNA extracted from just a few cells, pushing the limits of current sequencing technologies. Advanced mass spectrometers and nanoscale resonators can detect femtogram-level differences, revealing chemical changes invisible at larger scales. The femtogram symbolizes the reach of modern science into realms once thought beyond measurement. As techniques continue to improve, femtogram-level precision will become increasingly common in nanotechnology and biophysics.