11판/11. 굴림운동, 토크, 각운동량

11-55 할리데이 11판 솔루션 일반물리학

짱세디럭스 2024. 6. 16. 14:26
{R=0.48[m]h=0.34[m]N=2.00mgI=βmr2 \begin{cases} R&=0.48\ut{m}\\ h&=0.34\ut{m}\\ N&=2.00mg\\ I&=\beta mr^2 \end{cases} mvf2R=ΣFR=Nmg=2mgmg=mg \begin{aligned} {m{v_f}^2\over R}&=\Sigma F_R\\ &=N-mg\\ &=2mg-mg\\ &=mg\\ \end{aligned} vf2=gR{{v_f}^2}=gR v=ωr,v=\omega r, ΔΣE=0\Delta \Sigma E=0 0=mgΔy+12IΔ(ω2)+12mΔ(v2)=mg(h)+12(βmr2)(vfr)2+12mvf2=2gh+βvf2+vf2 \begin{aligned} 0 &=mg\Delta y+{1\over2}I\Delta \br{\omega^2}+{1\over2}m\Delta \br{v^2}\\ &=mg\br{-h}+{1\over2}\br{\beta mr^2}\br{v_f\over r}^2+{1\over2}m{v_f}^2\\ &=-2gh+{\beta }{v_f}^2+{v_f}^2\\ \end{aligned} 2gh=(1+β)vf2=(1+β)gR \begin{aligned} 2gh &=\br{1+\beta }{v_f}^2\\ &=\br{1+\beta }gR\\ \end{aligned} β=2hR1=5120.41666666666666670.42 \begin{aligned} \beta &={2h\over R}-1\\ &={5\over 12}\\ &\approx 0.4166666666666667\\ &\approx 0.42\\ \end{aligned}