Final answer:
The change in potential energy of the spring is 125.91 J.
Step-by-step explanation:
To find the change in the potential energy of the spring, we can use the formula for elastic potential energy: PE = 1/2 k x^2, where PE is the potential energy, k is the stiffness of the spring, and x is the change in length of the spring.
In this case, the stiffness of the spring is 830 N/m and the change in length is from 0.22 m to 0.8 m. So, the change in potential energy is:
PE = 1/2 (830 N/m) ((0.8 m)^2 - (0.22 m)^2) = 125.91 J.