NIST SP 811 factors: kinetic energy of 2 slug at 10 ft/s = 100 ft·lbf = 135.58 J

Tool	Formula with Units
Source	Thompson, A., and Taylor, B. N. (2008). Guide for the Use of the International System of Units (SI). NIST Special Publication 811, National Institute of Standards and Technology, Gaithersburg, MD. Appendix B.8 (slug, ft, ft·lbf).
Level	Undergraduate

Problem

A body of mass 2 slug moves at 10 ft/s. Evaluate E = ½ m v² in US customary units and convert it to joules through the base units.

Example select 'Kinetic energy ½ m v²' (fills m = 2 slug, v = 10 ft/s, formula 0.5 * m * v^2, result unit J)

E = 100 ft·lbf = 135.58179 J (SP 811: 1 ft·lbf = 1.3558179483314 J, 1 slug = 14.5939029 kg)
Derived SI unit N·m, also J; base form kg·m²·s⁻²

Loaded from the Example select; not the default case. Requesting an incompatible result unit (for example m) is refused by the dimensional check.