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

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

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Theory of Machine
For an isochronous Hartnell governor (where r₁ and r₂ = Maximum and minimum radius of rotation of balls respectively, S₁ and S₂ = Maximum and minimum force exerted on the sleeve respectively, and M = Mass on the sleeve)

S₁/S₂ = r₁/r₂
(m.g - S₁)/(m.g - S₂) = r₂/r₁
(m.g + S₁)/(m.g + S₂) = r₁/r₂
S₂/S₁ = r₁/r₂

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