A spring with an 772kg mass and a damping constant 5 kgs can

A spring with an 772-kg mass and a damping constant 5 (kg/s) can be held stretched 1 meters beyond its natural length by a force of 2 newtons. If the spring is stretched 2 meters beyond its natural length and then released with zero velocity, find the mass that would produce critical damping.

Force = spring constant * distance

Spring constant k = force / distance = 2 Newton per metre