Aspring is compressed to a displacement of -3.9 m from equilibrium. then the spring is released and allowed to stretch to a displacement of -1.5 m from equilibrium. the spring constant is 11 n/m. what best describes the work involved as the spring stretches? 71 j of work is performed on the spring. the spring performs 140 j of work the spring performs 71 j of work. 140 j of work is performed on the spring.

The elastic potential energy stored by a spring is

where  is the spring's constant and x is the displacement of the spring with respect its rest position.

In the problem we have two situations: situation 1 (initial condition), where the spring has a displacement of , and situation 2 (final condition), where the spring has a displacement of . The work performed by the spring corresponds to its loss in elastic potential energy:


this work has positive sign, because it is performed by the spring (in factm the spring is releasing from a position of higher potential energy to a position with less potential energy). 

Therefore, the correct answer is The spring performs 71 J of work.