If a 2 kg ball is moving at 6 m/s to the right and then hits a wall and bounces back at - 4 m/s (left), what is the change in momentum (in kg*m/s)?

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?