A $600$ N weight is hanging from the end of a cable with a total volume of $0\mathrm{.}5$ m$\mathrm{\text{'}\; 3},$ causing a stress of $20,000/$m$\text{'}$ in the cable. If the Young's modulus of the cable is $36,000$ N$/$m$\text{'},$ how much strain energy is stored in the cable?