Convert Poundal to Femtonewtons
Convert Poundal (pdl) to Femtonewtons (fN) instantly and accurately.
Conversion Formula
fN = pdl × 138254954400000
About Poundal
The poundal (pdl) is the force unit of the foot-pound-second absolute system - the force to accelerate 1 pound at 1 ft/s² - approximately 0.1383 N. Introduced in 1877 by Thomson and Tait as the FPS analogue of the CGS dyne (1 dyn = 1 g·cm/s²; 1 pdl = 1 lb·ft/s²). The poundal is distinct from pound-force: since standard gravity = 32.174 ft/s², 1 lbf = 32.174 pdl. It survives in older British engineering texts and early 20th-century thermodynamics literature, but is otherwise obsolete. 1 pdl = 0.138254954376 N = 1/32.174 lbf.
About Femtonewtons
A femtonewton (fN) is 10⁻¹⁵ N - the force scale of single-molecule biology. RNA polymerase exerts a stall force of ~14-25 fN while transiting DNA at 10-50 bp/s. Myosin V motor proteins step 37 nm with ~1-3 fN per head. The viscous drag on a 100 nm nanoparticle moving at 1 µm/s through cytoplasm is ~0.2-0.5 fN. Optical tweezers with back-focal-plane detection resolve sub-femtonewton forces, enabling measurement of single-enzyme output. AFM receptor-ligand unbinding (e.g., biotin-streptavidin) gives adhesion forces of 100-300 fN. 1 fN = 10⁻¹⁵ N.
Quick Reference Table
| Poundal (pdl) | Femtonewtons (fN) |
|---|---|
| 1 pdl | 1.383 × 1014 fN |
| 2 pdl | 2.765 × 1014 fN |
| 5 pdl | 6.913 × 1014 fN |
| 10 pdl | 1.383 × 1015 fN |
| 25 pdl | 3.456 × 1015 fN |
| 50 pdl | 6.913 × 1015 fN |
| 100 pdl | 1.383 × 1016 fN |