the difference between a direct force and an indirect force is a) the strength of the force b) the distance at which the force is acting c) the mass of the object involved d) the acceleration of the force

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.