A simplified model of a bungee jump can be analyzed in two sections: a freefall section in which the bungee cord has not yet begun stretching and a section in the lower portion of the jump in which the bungee cord stretches and exerts a force on the jumper. The cord is assumed to exert zero force on the jumper until its length exceeds its maximum unstretched length. Determine the maximum unstretched length of a bungee cord of spring constant 100 N/m such that a 70-kg jumper will not hit the ground when jumping from a height of 45 m.