Which of the following practices is an effective engineering method for reducing unwanted friction in machine bearings?
Answer and explanation
Correct answer: D. Applying lubricating grease or oil between moving parts
- Step 1: Lubricants create a thin fluid film between metal surfaces, preventing direct asperities contact. Step 2. This replaces solid-solid friction with much lower fluid friction. Answer: Applying lubricating grease or oil between moving parts. Why not the others: Roughening surfaces and adding sand increase friction; increasing mass increases normal force and friction.
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