1. Decide if each of the following can be modeled as an incompressible flow or a compressible flow:
(a) the take-off and landing of commercial airplanes
(b) the airflow around an automobile
(c) the flow of air in a hurricane
(d) the airflow around a baseball thrown at 100 mi/h
2. Write all the non-zero terms of Dr/Dt for a stratifled flow in which:
(a) r ¼ r(z) and V ¼ z(2 - z)i
(b) r ¼ r(z) and V ¼ f(x, z)i þ g(x, z)j