Topic: Machine Design
A ball bearing has a dynamic load rating of 60,000 N and experiences a load of 20,000 N. The expected life in million revolutions is:
- A. 8
- B. 18
- C. 27
- D. 64
Answer: C. 27
Explanation: For ball bearings, the expected rating life in millions of revolutions is given by $L_{10} = \left(\frac{C}{P}\right)^3$.
$L_{10} = \left(\frac{60000}{20000}\right)^3 = (3)^3 = 27$ million revolutions.