slug
Massexact by definition
The slug is the mass that one pound-force accelerates at one foot per second squared, which makes it exactly 14.5939029372064 kilograms, or about 32.174 pounds. It exists so that F = ma can be written in customary units with no conversion constant in it at all.
Watch out: The slug is a mass, the pound-force is a force, and the pound is a mass. Air density in US aerodynamics is 0.002377 slug/ft³ at sea level, the same air as 0.0765 lb/ft³; the two numbers differ by the factor 32.174 and swapping them silently is a classic wind-tunnel error. The competing convention keeps pounds for mass and carries g_c = 32.174 lb·ft/(lbf·s²) through every equation instead. Pick one and stay in it.
| 1 | 14.593903 |
Proposed around 1900 by Arthur Mason Worthington and adopted slowly, mostly by aerodynamicists. The name is a joke about something heavy and sluggish, and it stuck because the alternative names on offer were worse.
One slug in every mass unit
| 8.78865e+27 | unified atomic mass unit (dalton) (u) | |
| 1.45939e+16 | picogram (pg) | |
| 14,593,900,000,000 | nanogram (ng) | |
| 14,593,900,000 | microgram (μg) | |
| 14,593,900 | milligram (mg) | |
| 1,459,390 | centigram (cg) | |
| 225,218 | grain (gr) | |
| 72,969.5 | metric carat (ct) | |
| 14,593.9 | gram (g) | |
| 9,384.1 | pennyweight (dwt) | |
| 8,236.56 | dram (dr) | |
| 514.785 | ounce (oz) | |
| 469.205 | troy ounce (oz t) | |
| 39.1004 | troy pound (lb t) | |
| 32.174 | pound (lb) | |
| 14.5939 | kilogram (kg) | |
| 2.29815 | stone (st) | |
| 1 | slug (slug)this unit | |
| 0.32174 | US hundredweight (cwt) | |
| 0.287268 | UK long hundredweight (cwt (UK)) | |
| 0.145939 | quintal (q) | |
| 0.016087 | US short ton (ton) | |
| 0.0145939 | metric tonne (t) | |
| 0.0143634 | UK long ton (long ton) | |
| 0.0000145939 | kilotonne (kt) | |
| 1.45939e-08 | megatonne (Mt) | |
| 1.45939e-11 | gigatonne (Gt) | |
| 2.44364e-24 | Earth mass (Mearth) | |
| 7.33948e-30 | solar mass (Msun) |