47. (a) We take the initial gravitational potential energy to be Ui= 0. Then the final gravitational potential energy is Uf= –mgL, where Lis the length of the tree. The change isUUmgLfi−=−=−=−×((.25122 9 103kg) 9.8 m sm)J .2di(b) The kinetic energy is 22211(25 kg)(5.6 m/s)3.9 10 JKmv===×.(c) The changes in the mechanical and thermal energies must sum to zero. The change in
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This note was uploaded on 05/17/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.