A pen contains a spring with a spring constant of 257 N/m. When the tip of the pen is in its retracted position, the spring is compressed 5.1 mm from its unstrained length. In order to push the tip out and lock it into its writing position, the spring must be compressed an additional 6.1 mm. How much work is done by the spring force to ready the pen for writing

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?