You operate a bungee-jumping business offering customers a high-adrenalin jump in which they drop within 5.0 m of (but do not touch) the river 65.0...

You operate a bungee-jumping business offering customers a high-adrenalin jump in which they drop within 5.0 m of (but do not touch) the river 65.0 metres below a bridge. The bungee cord, which obeys Hooke’s law, is 30.0 m long and has a spring constant of 150 N m-1. One end is attached to the bridge by a length L of inextensible cord. This length L is adjusted according to the mass of the jumper. Calculate the length L required to bring the ankles of a 60.0 kg jumper momentarily to rest 5.0 m above the river. Assume the initial drop velocity from the bridge is zero and neglect friction and drag forces. (Do these approximations endanger the safety margin of your calculations?)