The critical speed of a trommel (N) is related to its dia D. as _____________________? August 22, 2021February 18, 2019 by admin The critical speed of a trommel (N) is related to its dia D. as _____________________? A. N ∝ 1/√D B. N ∝ √D C. N ∝ D D. N ∝ 1/D