Theory of Machine
A body is said to be under forced vibrations, when

No external force acts on a body, after giving it an initial displacement
There is a reduction in amplitude after every cycle of vibration
None of these
A body vibrates under the influence of external force

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

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Theory of Machine
In a cam drive with uniform velocity follower, the sharp corners of the displacement diagram are rounded off at the beginning and at the end of each stroke. This is done

Because of difficulty in manufacturing cam profile
Because the uniform velocity motion is a partial parabolic motion
In order to have acceleration in beginning and retardation at the end of stroke within the finite limits
Because of loose contact of follower with cam surface

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