7-21 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} m&=5.0\ut{kg}\\ F(x)&=\text{in Graph}\\ \end{cases} $$ $$W_{i\rarr f}=\int_{i}^{f} \vec F \cdot \dd \vec S,$$ $$ \begin{aligned} W_{0\rarr 8}&=\int_{0}^{8} F \cdot \dd x\\ &=\bra{\frac{1}{2}\cdot(2\ut{m}+4\ut{m})\cdot20\ut{N}}-\(\frac{1}{2}\cdot2\ut{m}\cdot10\ut{N}\)\\ &=50\ut{J}\\ &=5.0\times10\ut{J} \end{aligned} $$