A slender shaft supported on two bearings at its ends carries a disc with an eccentricity e from the axis of rotation. The critical speed of the shaft is Nc. If the disc is replaced by a second one of same mass but mounted with an eccentricily 2 e, then the critical speed of the shaft in the second case is

A slender shaft supported on two bearings at its ends carries a disc w

1.	A slender shaft supported on two bearings at its ends carries a disc with an eccentricity e from the axis of rotation. The critical speed of the shaft is Nc. If the disc is replaced by a second one of same mass but mounted with an eccentricily 2 e, then the critical speed of the shaft in the second case is
A.	Nc/2
B.	Nc/2
C.	Nc
D.	2 Nc
Answer» D. 2 Nc

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