4. An object with a mass m = 1 kg is positioned on a flat plate. The flat plate undergoes simple harmonic oscillations vertically with a period T = 0.5 s and an amplitude A = 0.02 m. Determine: (a) the positive pressure exerted by the object on the flat plate when the displacement is at its maximum; (b) the amplitude the flat plate must reach for the heavy object to initiate jumping away from it.