I thought more along the lines of applied physics that geoffkait indulges in.
Cute discussion starts on page 2. (from paragraph 2.2)
http://www.physics.princeton.edu/~mcdonald/examples/tirepump.pdf
Cute discussion starts on page 2. (from paragraph 2.2)
http://www.physics.princeton.edu/~mcdonald/examples/tirepump.pdf