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Estimate of the number of men n needed to pull a sledge with a 123-ton stone corresponding to four different lubrication conditions: (A) sliding on a dirt road (12), (B) sliding on wet wood (1), (C) sliding on an ice path without a lubricating water film (15), and (D) Sliding on an iced road with a lubricating water film (15). F is the towing force. (E) Comparison of the coefficient of the friction μ and the number of men n needed for conditions A–D.
