A 0.1 kilogram mass is dropped from a height of 180 meters. What is the gravitational potential energy of the mass? 92.3 Joules
176.6 Joules
17.6 Joules
102.3 Joules

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.