The discussions between Beaty and Denker about airplane lift and its
eventual effect on the ground remind me of a back-of-chapter question I saw
in a general physics textbook:
A bird is sitting on a perch in a cage. The cage is on a scale. The bird
begins to fly around in the cage. What will the scale register?
I may not be remembering the question exactly, but it was something like
that. You'll have to make whatever reasonable unstated assumptions you
like, but I would like to explicitly consider the following issues:
(i) What difference will it make if the cage is sealed (preventing air
circulation to and from the outside) versus ventilated?
(ii) What will the scale register: As the bird leaves the perch? As it
hovers in the air helicopter-style? If it stops flapping and plummets
towards the floor of the cage?
Don't think I have any answers, and yes the question is too open-ended and
can be nit-picked to death. But I think it's interesting nevertheless, so
let's hear your thoughts. Carl
Dr. Carl E. Mungan, Assistant Professor http://www.uwf.edu/~cmungan/
Dept. of Physics, University of West Florida, Pensacola, FL 32514-5751
office: 850-474-2645 (secretary -2267, FAX -3323) email: cmungan@uwf.edu