The 75-kg man bungee jumps off the bridge at A with an initial downward speed of 1.5 m/s....

The 75-kg man bungee jumps off the bridge at A with an initial downward speed of 1.5 m/s. Determine the required unstretched length of the elastic cord to which he is attached in order that he stops momentarily just above the surface of the water. The stiffness of the elastic cord is k = 80 N/m. Neglect the size of the man.