7-25 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} v_0&=0\\ \vec F&=315\i\ut{N}\\ \theta&=20\degree\\ S&=9.2\ut{m} \end{cases} $$ $$ \begin{aligned} K&=K_0+W\\ &=W~~(\because v_0=0)\\ &=\vec F \cdot \vec S\\ &= FS\cos\theta\\ &=2898\cos20\degree\ut{J}\\ &\approx 2723.2292150375624\ut{J}\\ &\approx 2.7\times10^3\ut{J}\\ &\approx 2.7\ut{kJ}\\ \end{aligned} $$