10-8 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} r&=0.20\ut{m}\\ I&=0.050\ut{kg\cdot m^2}\\ m&=2.0\ut{kg}\\ P&=3.0\ut{N}\\ \end{cases} $$ $$ \begin{cases} \Sigma F&=ma\\ \Sigma \tau&=I\alpha\\ \end{cases} $$ $$ \begin{cases} P-T&=ma\\ rT&=I\alpha\\ a&=r\alpha \end{cases} $$ $$ \begin{aligned} \alpha&=\frac{r P}{I+mr^2}\\ &=\frac{60}{13}\ut{rad/s^2}\\ &\approx 4.615384615384615\ut{rad/s^2}\\ &\approx 4.6\ut{rad/s^2}\\ \end{aligned} $$