Theory of Machine
Whirling speed of the shaft is the speed at which

Torsional vibrations occur
Combination of transverse and longitudinal vibration occurs
Shaft tends to vibrate vigorously in transverse direction
Shaft tends to vibrate in longitudinal direction

ANSWER DOWNLOAD EXAMIANS APP

Theory of Machine
The contact ratio is given by

(Length of the path of approach)/(Circular pitch)
(Length of path of recess)/(Circular pitch)
(Length of the arc of contact)/(Circular pitch)
(Length of the arc of approach)/cosφ

ANSWER DOWNLOAD EXAMIANS APP