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hydraulic jack



A student of mine was thinking about hydraulic systems and brought in his floor jack. We measured the diameter of the input and output pistons and the distance each moved during one pass. We hoped that the total volume would be the same, i.e., pi r2 h of one would equal pi r2 h of the other, where h is the distance each piston moved during one pass. However, the output volume is 20-25% greater.

Anyone know what we're missing?

____________________________________________
Robert Cohen; rcohen@po-box.esu.edu; 570-422-3428; http://www.esu.edu/~bbq
Physics, East Stroudsburg Univ., E. Stroudsburg, PA 18301