I'm recreating a calculation from this paper. The authors calculated the angular momentum (L) of a spinning disc with mass = 114.7 grams (0.1147 kg) and radius = 4.75 cm (0.0475 m). The disc spins at 11,000 rpm (~1151 rads/s). They give L as "0.0474 J-s".
However, when I calculate L, I get something totally different. Here's my steps.
L = I * Omega, where I is moment of inertia(MOI) and Omega is angular velocity.
Using the equation for MOI of a disc using kilograms and meters I get I = 1/2 * (0.1147) * (0.0475^2)
To calculate Angular Velocity using radians/sec, I get L = 0.00012939 * 1151.917 = 0.14905 kg-m^2 / second
Which is nowhere near the authors' 0.0474 J-s. I suspect I am making an error in my use of units, but my understanding is that J-s (Joule-seconds) are equivalent to kg-m^2/sec (kilogram-meters squared per second). Am I confused about units, or did I make a calculation error?
EDIT: Solved! It appears the paper itself was wrong. Thanks to JEB for pointing this out.