Talk:International System of Units/Archives/11/2009
Latest comment: 14 years ago by Dger in topic SI missing
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SI missing
Dear [type your name here],
Quick word about one "sort of unit" my physic teacher use to teach us: radians and steradians.
Best regards, virtualgot@hotmail.com —Preceding unsigned comment added by 61.173.98.133 (talk) 09:41, 10 November 2009 (UTC)
- These used to be classed as Supplementary Units but are now Derived Units. They are both dimensionless ratios. E.g., a radian is the ratio of arclength (in metres) to radius (also in metres) and therefore the units are m/m, which equals 1. They can be included or excluded when they add clarity to a measure. For example, angular velocity can be rad/s or simply s-1. DGERobertson (talk) 00:08, 11 November 2009 (UTC)