Topic: Theory of Machines
A perfectly balanced rotor shaft supported between short bearings at both ends shows a deflection of 2 mm at middle. Then the critical speed of the shaft in rpm will be nearly,
- A. 335
- B. 670
- C. 2010
- D. 1340
Answer: B. 670
Explanation: Omega = $\sqrt{g / delta}$ = $\sqrt{9.81 / 0.002}$ = 70.035 rad/s. Critical speed N_c = (60 * Omega) / (2 * pi) = (60 * 70.035) / (2 * 3.14) = 669.12 rpm, which is approximately 670 rpm.