Consider a hanging spring of negligible mass that does not obey Hooke's law. When the spring is extended by a distance x, the force exerted by the spring has magnitude 2x, where is a constant. The spring is not extended when a block of mass m is attached to it. The block is then released, stretching the spring as Xmax it falls. (Neglect air drag.) What is the acceleration of the block at the instant the spring stretches the maximum distance xmax? m |g