A bungee jumper has mass m=96.7kg and uses a bungee cord of unstretched length l=11.9 m. The cord has negligible mass and a force constant k=327 N/m, which means that when its extension is ?l the force it applies on the jumper is F=?k?l. The bungee jumper falls off a bridge. Treat her as a point mass and ignore dissipation. (a) What is the bungee jumper's speed when she has fallen by exactly the unstretched length of the cord? (b) What elastic force does the cord apply at this instant? (c) By considering energy conservation, or otherwise, calculate the extension ?l of the cord at the lowest point of her fall. (d) Calculate the magnitude of the jumper's acceleration at the lowest point of her fall.