The law of conservation of energy (6-28)
Question
Change in the \(\textbf{potential energy}\) \(U\) associated with an object during its motion
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Review
Equation 6-28 suggests that we broaden our definition of energy to include both total mechanical energy \((E = K + U)\) and internal energy \(E_{\mathrm{other}}\). In this case, we have to expand the system to include not only the object and the sources of the conservative forces that produce \(\Delta{U}\), but also the sources of the nonconservative forces that result in \(\Delta{E}_{\mathrm{other}}\) (like your hand in the case of the thrown pencil). As the object moves, \(K\), \(U\), and \(E_{\mathrm{other}}\) can all change values, but the sum of these changes is zero: One kind of energy can transform into another, but the total amount of energy of all forms remains the same. This is the most general statement of the \(\textbf{law of conservation of energy}\).
