Fleas are agile, wingless insects that feed on the blood of their hosts. Although they are typically 2–3 mm long with a mass of 3.9×10−4 kg , they have an astonishing ability to jump when threatened. Their propulsion, which can briefly produce accelerations more than 100 times that of gravity, comes not from muscles but, in fact, from an elastomeric protein called resilin, which acts as a spring. Given that the typical launch velocity of a flea is about 1 m/s, what total energy must be stored in the resilin just before the flea jumps?