8-56 할리데이 11판 솔루션 일반물리학

$$ \put \begin{cases} U : \text{Potential Energy}\\ \end{cases} $$ $$ \begin{cases} U_A&=60\ut{J}\\ W_{A\rarr B}&=+35\ut{J} \end{cases} $$ $$W_{i\rarr f}=-\Delta U_{i\rarr f},$$ $$U_A-U_B=W_{A\rarr B}$$ $$ \begin{aligned} U_B&=U_A-W_{A\rarr B}\\ &=60-(+35)\\ &=25\ut{J} \end{aligned} $$