A block resting on the horizontal surface executes SHM in horizontal plane with amplitude A The frequency of oscillation for which the block just starts to slip is (μ = coefficient of friction, g = gravitational acceleration)

When restoring force will become equal to the frictional force block will start to slip.∴     Restoring force = Friction force⇒                           kA=μmg                             ∵Frestoring =-kx                …(i)Now,    frequency, f=12πkmFrom Eq. (i), we get                              f=12πμgA