Remember force=springconstant x extension (f = k xx)
1. if a spring starts at a length of 13cm, and it extends to a length of 21cm - what is the
extension of the spring? can you convert you answer into meters?

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?