Solve the below problem:
Q: As shown in Fig. a spring having an initial unscratched length of l0 is stretched by a force F applied at its end. The stretched length is l. By Hooke's law, the force is linearly related to the spring extension by F = k (l - l0), where k is the stiffness. If stiffness is constant
(a) Obtain an expression for the work done in changing the spring's length from l1 to l2.
(b) Evaluate the work done, in J, if l0 = 3cm, l1 = 6 cm, l2 = 10cm, and the stiffness is k = 104 N/m.
