What component reduces friction by allowing smooth rolling between surfaces via balls or rollers?

• A. Bearings
• B. Lubricants
• C. Gears
• D. Shafts

Answer: (A)

Bearings are designed to allow parts to move smoothly relative to each other by using rolling elements—balls or rollers—between inner and outer races. This rolling contact turns what would be sliding friction into much lower rolling friction, letting components rotate or slide with less resistance and wear. Lubricants reduce friction by forming a protective film but don’t create the rolling interface themselves. Gears transfer torque through meshing teeth, and shafts transmit power, but neither provides the rolling-contact mechanism. So the component that reduces friction via balls or rollers is the bearing.