2012_1061_Lecture_Ch_078

Mechanical energy if only mechanical forces are doing

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Unformatted text preview: − → =− F net · d ￿ = −Wnet 1 ∆K + ∆U = 0 [conservative forces only] (K2 − K1 ) + (U2 − U1 ) = 0 [conservative forces only] Conservation of Total Mechanical Energy  Total Mechanical Energy E =K +U K2 + U2 = K1 + U1 [conservative forces only] E2 = E1 = [conservative forces only] constant  Principle of conservation of Mechanical Energy If only mechanical forces are doing the work , the total mechanical energy of a system neither increases no decreases in any process. It stays constant- it is conserved. Falling Rock 1 2 E = K + U = mv1 + mgy 2 1 1 2 2 mv1 + mgy1 = mv2 + mgy2 2 2 [gravity only] 1 2 0 + mgh = mv2 + 0 2 v2 = ￿ 2gh Exam...
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