Theory of Machine
The contact ratio is given by

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

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Theory of Machine
When a mass of a critically damped single degree of freedom system is deflected from its equilibrium position and released, then it will

Oscillate with increasing time period
Return to equilibrium position without oscillation
Oscillate with constant amplitude
Oscillate with decreasing amplitude

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