A bungee cord is essentially a very long rubber band that can stretch up to four times its unstretched length. However, its spring constant varies over its stretch [see Menz, P. G. "The Physics of Bungee Jumping." The Physics Teacher (November 1993) 31: 483-487]. Take the length of the cord to be along the x-direction and define the stretch x as the length of the cord l minus its un-stretched length l0 ; that is, x = l − l0 (see below). Suppose a particular bungee cord has a spring constant, for 0 ≤ x ≤ 4.88 m , of k1 = 204 N/m and for 4.88 m ≤ x , of k2 = 111 N/m. (Recall that the spring constant is the slope of the force F(x) versus its stretch x.) (a) What is the tension in the cord when the stretch is 16.7 m (the maximum desired for a given jump)?

(b) How much work must be done against the elastic force of the bungee cord to stretch it 16