During a circus act, one performer swings upside down hanging from a trapeze holding another, also upside-down, performer by the legs. If the upward force on the lower performer is three times her weight, how much (in m) do the bones (the femurs) in her upper legs stretch? You may assume each is equivalent to a uniform rod 30.0 cm long and 1.70 cm in radius. Her mass is 57.5 kg.