Define extiency of a liever

Yvette hangs a 2.4kg bird feeder in the middle of a rope tied between two trees. the feeder creates a tension of 480 n in each side of the the rope.

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.

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?