An object with mass $4\mathrm{.}0$ kg is executing simple harmonic motion, attached to a spring with spring constant $290$ N$/$m$.$ When the object is $0\mathrm{.}018$ mm from its equilibrium position, it is moving with a speed of $0\mathrm{.}40$ m$/$s$.$ Calculate the amplitude of the motion. Calculate the maximum speed attained by the object.