A disturbing mass m₁ attached to the rotating shaft may be balanced by a single mass m₂ attached in the same plane of rotation as that of m₁, such that (where r₁ and r₂ are the radii of rotation of m₁ and m₂ respectively)
m₁r₂ = m₂r₁
m₁r₁ = m₂r₂
m₁m₂ = r₁r₂
None of these
