In a rear-wheel car, the engine power is transferred to the rear wheels by a drive shaft. The drive shaft has joints, just as your arms and legs have. The joints let the shaft move up and down as the wheels go over bumps and holes. Where the drive shaft meets the rear axles, there is another set of gears called the differential. These gears let each wheel turn at its own speed when it is necessary. if the car is turning a corner, the outside wheel has to turn faster than the inside one because it has further to travel.

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