Pulley Ridge Pulley Ridge Pulley Ridge is a mesophotic coral reef system off the shores of the continental United States. The reef rests on sunken barrier islands and lies 100 miles west of the Tortugas Ecological Reserve and stretches north about 60 miles at depths ranging from 60–80 meters. Pulley Ridge was originally discovered in 1950 during a dredging operation conducted by an academic group from Texas. While well known to fishermen, this remarkable habitat remained undiscovered by scientists until 1999 when the U.S. Geological Survey (USGS) and graduate students from the University of South Florida happened upon it. This reef system,
Block and tackle output force), formula_5 is the ideal mechanical advantage of the system (which is the same as the number of segments of line extending from the moving block), and formula_6 is the mechanical efficiency of the system (equal to one for an ideal frictionless system; a fraction less than one for real-world systems with energy losses due to friction and other causes). If formula_7 is the number of sheaves in the purchase, and there is a roughly formula_8% loss of efficiency at each sheave due to friction, then: This approximation is more accurate for smaller values of formula_7 and formula_8. A