A 0.5 kg body falls from rest through 20 m and reaches 15 m/s. The work done against air resistance is (g = 9.8):

  1. 20.9 J
  2. 98 J
  3. 41.8 J
  4. 83.5 J
Answer

C) 41.8 J

Loss of PE = mgh = 98 J; gain of KE = 56.2 J; work against friction = 41.8 J. SLO P-11-B-32 · Application

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