You are designing exercise equipment to operate as shown in, where a person pulls upward o...

You are designing exercise equipment to operate as shown in, where a person pulls upward on an elastic cord. The cord behaves like an ideal spring and has an unstretched length of 31 cm. If you would like the torque about the elbow joint to be 81 N · m in the position shown, what force constant, k, is required for the cord?

FIGURE