5-39 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} m&=4.0\ut{kg}\\ \vec F_1 &= 3.0\i+4.0\j\ut{N} \end{cases} $$ $$ \begin{aligned} \vec a&=\frac{\Sigma \vec F}{m}\\ &=\frac{\vec F_1+\vec F_2}{m}\\ \end{aligned} $$ $$\ab{a}$$ $$\vec F_2 = -3.0\i-4.0\j\ut{N},$$ $$ \begin{aligned} \vec a_a&=\frac{\vec F_1+\vec F_2}{m}\\ &=0 \end{aligned} $$ $$\ab{b}$$ $$\vec F_2 = -3.0\i+4.0\j\ut{N},$$ $$ \begin{aligned} \vec a_b&=\frac{\vec F_1+\vec F_2}{m}\\ &=\frac{8}{4}\j\ut{m/s^2}\\ &=2\j\ut{m/s^2}\\ \end{aligned} $$ $$\ab{c}$$ $$\vec F_2 = 3.0\i-4.0\j\ut{N},$$ $$ \begin{aligned} \vec a_b&=\frac{\vec F_1+\vec F_2}{m}\\ &=\frac{6}{4}\i\ut{m/s^2}\\ &=1.5\j\ut{m/s^2}\\ \end{aligned} $$