Ball bearings are used in bicycles, cars, etc., because
- the actual area of contact between the wheel and axle is increased
- the effective of contact between the wheel and axle is increased
- the effective area of contact between the wheel and axle is reduced
- None of the above statements is correct
Explanation
Option (c) is correct
- Ball bearings are used to reduce friction between moving parts like the wheel and axle. Instead of direct surface contact (sliding friction), the balls introduce rolling motion, which has much less friction. More importantly, the contact between the balls and the surfaces occurs at very small points, not across a large surface. This significantly reduces the effective area of contact, thereby lowering resistance to motion. Thus, by converting sliding friction into rolling friction and minimizing the contact area, ball bearings make movement smoother and more efficient.
