A spring has stiffness of 100Nmm, the initial compression of the spring is 15mm, and it is then compressed to 65mm.

•1Nmm = 0.001Nm
•100Nmm = 100 X 0.001 = 0.1Nm
•Comp.1 = 15 mm = 0.015m
•Comp.2 = 65 mm = 0.065m

a) i-Find potential energy at 15mm.
ii- Find potential energy at 65mm.
b) Find the work done during compression.