The spring of a spring balance is 5.0 cm long when there is no weight on the balance, and it is 8.8 cm long with 8.0 N hung from the balance. How much work is done in stretching it from 5.0 cm to a length of 11.2 cm?
◦ 110 N∙cm
◦ 40 N∙cm
◦ 9.1 N∙cm
◦ 6.5 N∙cm