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Apassenger walks toward the rear of a moving train. describe her motion as seen from a reference point on the train. then describe it from a reference point on the ground

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.

Name two kinds of practical electric pumps.