5-47 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} m&=67\ut{kg}\\ T&\le400\ut{N}\\ g&=9.80665\ut{m/s^2} \end{cases} $$ $$\ab{a}$$ $$ \begin{aligned} mg&=657.04555\ut{N}\\ &\approx 6.6\times10^2\ut{N}\gt400\\ \end{aligned} $$ $$\text{Lope Broken}$$ $$\ab{b}$$ $$\Sigma \vec F = m\vec a,$$ $$ \begin{aligned} a&=\frac{\Sigma \vec F}{m}\\ &=\frac{T-mg}{m}\\ &=\frac{400-67g}{67}\\ &\approx -3.8365007462686567\ut{m/s^2}\\ &\approx -3.8\ut{m/s^2}\\ \end{aligned} $$