Ball bearings are used in bicycles, cars, etc., because

[amp_mcq option1=”the actual area of contact between the wheel and axle is increased” option2=”the effective area of contact between the wheel and axle is increased” option3=”the effective area of contact between the wheel and axle is reduced” option4=”None of the above statements is correct” correct=”option3″]

This question was previously asked in

UPSC IAS – 2013

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Ball bearings are used in bicycles, cars, etc., because they significantly reduce the effective area of contact between the moving parts (like the wheel and axle), thereby reducing friction.

Ball bearings replace sliding friction with rolling friction. Sliding friction occurs over a larger contact area between the axle and its housing. Ball bearings consist of spherical balls rolling between two races. The contact between the balls and the races is nearly point contact (in theory, or a very small ellipse in practice). This reduces the area experiencing friction and, crucially, replaces high sliding friction with much lower rolling friction.

Rolling friction is generally much less than sliding friction for the same load. By allowing parts to roll over each other via the balls, the overall frictional force opposing motion is greatly reduced, making movement easier and more efficient, and reducing wear and tear.

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