a bungee jumper momentarily comes to rest at the bottom of the dive before he springs back upward. at that moment, is the bungee jumper in equilibrium? explain.

yes, at that instant the bungee jumper is in equilibrium because the weight of the bungee jumper is balanced by the spring force as the spring force is acting in upwards direction and the weight of the jumper acts in downwards direction. So, that the net force on the jumper is zero and the net acceleration of the jumper is zero.