Tikz 05 : 단진자에 작용하는 힘 분해하기

다양한 방법이 있을 수 있지만 여기까지 그려봤습니다. 좌표를 계산할 때, 사칙연산 뿐만 아니라 sin, cos함수를 그대로 사용할 수 있습니다.

\documentclass[]{article}
\usepackage{tikz}

\usetikzlibrary{patterns}

\begin{document}
 \pagenumbering{gobble}
 \begin{figure}
  \begin{tikzpicture}[scale=1]
  
  \draw [pattern=north east lines ] (-2.5,0) rectangle (2.5,0.5);
  
   \draw [dashed] (0,0) --  (0,-5);
   
   \draw [thick] (0,0) -- (2*cos{60},-2*sin{60}) node[right]{$L$} --(4*cos{60},-4*sin{60});  
   
   \draw[] (0,-4.0) arc (-90:-60:4.0) ;
   
   \draw (0,-0.5) arc (-90:-60:0.5) node[below, xshift = -0.1cm ]{$\theta$};
   
   \filldraw (4*sin{30},-4*cos{30}) circle (5pt) node[right, xshift = +0.2cm  ]{$m$};
   
   \draw [ultra thick, ->, blue]   ((4*sin{30},-4*cos{30})  -- (4*sin{30},-4*cos{30} - 1.5) node[below]{$mg$};
   
   \draw (4*sin{30},-4*cos{30}-0.5) arc (-90:-60:0.5) node[below, xshift = -0.1cm ]{$\theta$};
   
   \draw [thick, ->, blue]   (4*sin{30},-4*cos{30})  -- (4*sin{30} + 1.5*cos{30}*sin{30}, -4*cos{30} -  1.5*cos{30}*cos{30}) node[right]{$mg \cos \theta$};
   \draw [thick, ->, blue]   (4*sin{30},-4*cos{30})  -- (4*sin{30} - 1.5*sin{30}*cos{30}, -4*cos{30} -  1.5*sin{30}*sin{30}) node[below, xshift = -0.3cm ]{$mg \sin \theta$};
   
   \draw [dashed, blue] (4*sin{30},-4*cos{30} - 1.5) -- (4*sin{30} + 1.5*cos{30}*sin{30}, -4*cos{30} -  1.5*cos{30}*cos{30});
   \draw [dashed, blue] (4*sin{30},-4*cos{30} - 1.5) -- (4*sin{30} - 1.5*sin{30}*cos{30}, -4*cos{30} -  1.5*sin{30}*sin{30});
  
  \draw [ultra thick, ->, blue]   (4*sin{30},-4*cos{30})  -- (4*sin{30} - 1.5*cos{30}*sin{30}, -4*cos{30} + 1.5*cos{30}*cos{30}) node[right,xshift = +0.1cm ]{$T$};
  
   
  \end{tikzpicture}
 \end{figure}
\end{document}