A power source supplies an electric potential difference of 9.0 V to the plates of a capacitor. The energy stored in the capacitor is 9.8 × 10–4 J. The dielectric constant of the dielectric in the capacitor is 5.1. The ratio of the area of the plates to the distance between the plates, rounded to two significant figures, is
× 10^5 m.

Quizlet says 5.4 as the answer. Not sure if that's right.

Why does the equilibrium position of the spring change when a mass is added to the spring? will the mass oscillate around the new equilibrium position of the spring or the previous position without a mass attached to the spring? if the equilibrium position of the spring changes by 20 cm (assuming no initial mass) when a mass is added to the spring with constant 4.9 kg/s^2, what is the mass of the object attached to the spring?