Bruce pulls a spring with a spring constant k=100 Nmk=100\, \dfrac{\text N}{\text m}k=100mNk, equals, 100, start fraction, star
t text, N, end text, divided by, start text, m, end text, end fraction, stretching it from its rest length of 0.20 m0.20\,\text m0.20m0, point, 20, start text, m, end text to 0.40 m0.40\,\text m0.40m0, point, 40, start text, m, end text.What is the elastic potential energy stored in the spring?