For some reason I divided by 2 more than was correct on two problems. Number 22 a 240 kg cart moving at 2.2 m/s has a KE of 240/2 x2.2 sqrd + 580 J and so eff = 580/ (100x12) = .48 or 48%
#34 The force 1200x 20sqrd/85 = 5650 N . mu = 5650/12000 = .47
These are examples of the dangers of inadequate sleep.
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