Topic: Machine Design
A journal bearing of radius 'r1' and radial clearance 'c1' has a sommerfeld number 's1'. Another journal bearing of radius 'r2' and radial clearance 'c2' has a sommerfeld number 's2'. All the other parameters remain the same for both bearings. If r2 = 2 r1 and c2 = c1 / 2, then s2 / s1 is
- A. 4
- B. 8
- C. 16
- D. 32
Answer: C. 16
Explanation: The Sommerfeld number S = (r/c)^2 * (mu * N / P). Since only radius and clearance are changing, S2 / S1 = (r2/c2)^2 / (r1/c1)^2. Substituting the values gives ((2*r1) / (c1/2))^2 / (r1/c1)^2 = (4)^2 = 16.