Hooke’s law describes a certain light spring of unstretched length cm. When one end is attached to the top of a doorframe and a -kg object is hung from the other end, the length of the spring is cm. (a) Find its spring constant. (b) The load and the spring are taken down. Two people pull in opposite directions on the ends of the spring, each with a force of N. Find the length of the spring in this situation.