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Unformatted text preview: Notes to accompany lecture on p. 70 of text. Case I. Consider a block of mass, M, falling through a height, h, ideally into a bath of water at temperature, T1. By ideally, we mean no splashing, wave generation or other energy wastes. If M = 1kg, T 1 = 298K, h = 3.0 m and C(bath) = 4.0 J/K, calculate T 2 , the final temperature of the bath. E block = Mg z = Mg ( z f- z i ) = Mg (0- h ) = - Mgh E bath = q + w = q + = C bath T E tot = E block + E bath = E block = - E bath C bath T = - (- Mgh ) = + Mgh T = 1.0 kg ( 29 9.8 m / s 2 ( 29 3.0 m ( 29 4 J / K = 7.4 K T 2 = 305.4 K Case II. Now block M, falling the same distance as in case I (and thereby having the same change in potential energy) now lifts a lighter block of mass, m, up a height, h (same distance through which M falls). If m = 500g = 0.50 kg, calculate T 2 . Note that we will use sys to denote block, M, as the system to distinguish it from block, m, which is part of the...
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- Fall '07