Answer & Solution
Answer: Option
A
Solution:
When we compare rolling contact bearings (ball/roller bearings) with sliding contact bearings (plain bearings), the biggest difference is in how they handle friction.
Rolling bearings use balls or rollers. This means the parts roll over each other, which makes it very easy to start moving (low starting friction) and also keeps the friction low while running (low running friction).
In contrast, sliding bearings rely on surfaces sliding against each other, which causes higher friction.
However, there is one exception – at very high speeds. Rolling bearings face issues like centrifugal force and lubrication problems, which increase friction. In some cases, they may even perform worse than sliding bearings at those speeds.
Why not other options?
B (Accuracy of shaft alignment): Both types of bearings need proper alignment. This is not a unique advantage of rolling bearings.
C (Small overall dimensions): Rolling bearings are not always smaller. Sometimes they can be larger depending on load and design.
So, D (All of the above) is not correct because only Option A is the clear, consistent advantage.
Therefore, from an exam/student point of view, the best answer is Option A.
