A special spring is constructed in which the restoring force is in the opposite direction to the displacement but is proportional to the cube of the displacement; i. e., F= -kx^3 this spring is placed on a horizontal frictionless surface. One end of the spring is fixed, and the other end is fastened to a mass M. The mass is moved so that the spring is stretched a distance A and then released. Determine each of the following in terms of k, A, and M
a) The potential energy in the spring at the instant the mass is released
b) the maximum speed of the mass
c) The displacement of the mass at the point where the potential energy of the spring and the kinetic energy of the mass are equal