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en/3.5.41.md
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| + | ### Statement | ||
| + | |||
| + | $3.5.41.$ [Insert the problem statement] | ||
| + | |||
| + | ### Solution | ||
| + | |||
| + | From $F=F_0\sin(\omega t)$ and the initial conditions $v=0$ and $x=0$ at $t=t_*$ (depending on when the particles are emitted), we have | ||
| + | |||
| + | \[a=\frac{F_0}{m}\sin(\omega t),\] | ||
| + | |||
| + | \[v=\frac{F_0}{m\omega}[\cos(\omega t_*)-\cos(\omega t)],\] | ||
| + | |||
| + | \[x=\frac{F_0}{m\omega^2}[\omega(t-t_*)\cos(\omega t_*)-\sin(\omega t)+\sin(\omega t_*)].\] | ||
| + | |||
| + | When $t_*=0$, we have | ||
| + | |||
| + | \[v=\frac{F_0}{m\omega}[1-\cos(\omega t)],\] | ||
| + | |||
| + | \[x=\frac{F_0}{m\omega^2}[\omega t-\sin(\omega t)].\] | ||
| + | |||
| + | Thus, the average velocity is $F_0/(m\omega)$, and the maximum velocity is $2F_0/(m\omega)$ achieved when $t=(2n-1)\pi/\omega$ and hence $x=F_0(2n-1)\pi/(m\omega^2)$, where $n$ is a positive integer. | ||
| + | |||
| + | When $t_*=\pi/(2\omega)$, we have | ||
| + | |||
| + | \[v=-\frac{F_0}{m\omega}\cos(\omega t),\] | ||
| + | |||
| + | \[x=\frac{F_0}{m\omega^2}[1-\sin(\omega t)].\] | ||
| + | |||
| + | Thus, the average velocity is $0$, and the maximum velocity is $F_0/(m\omega)$ achieved when $t=(2n-1)\pi/\omega$ and hence $x=F_0/(m\omega^2)$. | ||
| + | |||
| + | When $t_*=\pi/\omega$, we have | ||
| + | |||
| + | \[v=-\frac{F_0}{m\omega}[1+\cos(\omega t)],\] | ||
| + | |||
| + | \[x=-\frac{F_0}{m\omega^2}[\omega(t-\pi/\omega)+\sin(\omega t)].\] | ||
| + | |||
| + | Thus, the average velocity is $-F_0/(m\omega)$, and the maximum velocity is $0$ achieved when $t=(2n-1)\pi/\omega$ and hence $x=-2F_0(n-1)\pi/(m\omega^2)$. | ||
| + | |||
| + | #### Answer | ||
| + | |||
| + | [Insert a concise answer or boxed result] | ||
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| ### Statement | |||
| $3.5.41.$ [Insert the problem statement] | |||
| ### Solution | |||
| From $F=F_0\sin(\omega t)$ and the initial conditions $v=0$ and $x=0$ at $t=t_*$ (depending on when the particles are emitted), we have | |||
| \[a=\frac{F_0}{m}\sin(\omega t),\] | |||
| \[v=\frac{F_0}{m\omega}[\cos(\omega t_*)-\cos(\omega t)],\] | |||
| \[x=\frac{F_0}{m\omega^2}[\omega(t-t_*)\cos(\omega t_*)-\sin(\omega t)+\sin(\omega t_*)].\] | |||
| When $t_*=0$, we have | |||
| \[v=\frac{F_0}{m\omega}[1-\cos(\omega t)],\] | |||
| \[x=\frac{F_0}{m\omega^2}[\omega t-\sin(\omega t)].\] | |||
| Thus, the average velocity is $F_0/(m\omega)$, and the maximum velocity is $2F_0/(m\omega)$ achieved when $t=(2n-1)\pi/\omega$ and hence $x=F_0(2n-1)\pi/(m\omega^2)$, where $n$ is a positive integer. | |||
| When $t_*=\pi/(2\omega)$, we have | |||
| \[v=-\frac{F_0}{m\omega}\cos(\omega t),\] | |||
| \[x=\frac{F_0}{m\omega^2}[1-\sin(\omega t)].\] | |||
| Thus, the average velocity is $0$, and the maximum velocity is $F_0/(m\omega)$ achieved when $t=(2n-1)\pi/\omega$ and hence $x=F_0/(m\omega^2)$. | |||
| When $t_*=\pi/\omega$, we have | |||
| \[v=-\frac{F_0}{m\omega}[1+\cos(\omega t)],\] | |||
| \[x=-\frac{F_0}{m\omega^2}[\omega(t-\pi/\omega)+\sin(\omega t)].\] | |||
| Thus, the average velocity is $-F_0/(m\omega)$, and the maximum velocity is $0$ achieved when $t=(2n-1)\pi/\omega$ and hence $x=-2F_0(n-1)\pi/(m\omega^2)$. | |||
| #### Answer | |||
| [Insert a concise answer or boxed result] | |||