11-40 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} I&=2.4\times10^{-3}\ut{kg\cdot m^2}\\ \tau&=16\ut{N\cdot m}\\ t&=33\ut{ms}=33\times10^{-3}\ut{s} \end{cases} $$ $$\ab{a}$$ $$\vec \tau_\net=\dyt{\vec L}={\Delta L\over \Delta t},$$ $$ \begin{aligned} L_f&=\Delta L\\ &=\tau t\\ &={66\over 125}\ut{kg\cdot m^2/s}\\ &=0.528\ut{kg\cdot m^2/s}\\ &\approx 0.53\ut{kg\cdot m^2/s}\\ \end{aligned} $$ $$\ab{b}$$ $$L = I\omega,$$ $$ \begin{aligned} \omega_f &={L_f\over I}\\ &=220\ut{rad/s}\\ &=2.2\times10^2\ut{rad/s}\\ \end{aligned} $$