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Chapter 27 - 27.54

54. Using Eq. 7-48 and Eq. 27-22, the rate of change of mechanical energy of the piston-Earth system, mgv ,

must be equal to the rate at which heat is generated from the coil: mgv = i 2 R .Thus

v =

i 2 R

(0 . 240 A) 2 (550 Ω)

(12 kg) (9 . 8m / s 2 )

=0 . 27 m / s .