Many swimmers in the 2008 Beijing Olympics wore (Speedo) body suits it might have made a difference in breaking many world records ( Figure). Australian Cathy Freeman wore a full body suit in the 2000 Sydney Olympics and won a gold medal in the 400-m race. Bicycle racers and some swimmers and runners wear full bodysuits. The dimples on golf balls are being redesigned, as are the clothes that athletes wear. Substantial research is under way in the sporting world to minimize drag. Typical Values of Drag Coefficient C Object For this reason, during the 1970s oil crisis in the United States, maximum speeds on highways were set at about 90 km/h (55 mi/h).
The most fuel-efficient cruising speed is about 70–80 km/h (about 45–50 mi/h). At highway speeds, over 50% of the power of a car is used to overcome air drag.
Notice that the drag coefficient is a dimensionless quantity. Figure lists some typical drag coefficients for a variety of objects. The drag coefficient can depend upon velocity, but we assume that it is a constant here.
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