Creating a Free Body Diagram in TikZ

Question

I'm trying to create a free body diagram of an an object, more specifically the Orion spacecraft. I'm trying to create a diagram that consists of the vectors with F_g pointing downwards, F_D (drag) pointing at an angle similar to T in this image

I don't really know where to start.

Answer 1

First of all, welcome to TeX.SE.

You are probably wondering why your question got down voted. The problem mainly is that you are throwing in a problem, but are not showing that you made any effort to solve this. While this site is intended to help with specific problems it is not intended to do your work for you. I suppose you (and not someone else) tagged the question tikz-pgf, so you could use a searching website of your choice and search for, say tikz manual. This would probably yields something like this:

• The manual for TikZ and PGF. There you have about 700 pages of manual, including 5 very extensive tutorials to get you started.
• A very minimal introduction to TikZ. In case you don't want to read much, these 24 pages cut right to it, you should get the basic ideas quite fast.

After starting to read at least one of these, start trying out things:

• how to draw a triangle,
• how to fill it,
• how to draw a line at an angle,
• how to get an arrow head, and so on.

You will really only get it by trying. And then, if you really run into a wall, and you really can't figure it out, feel free to ask here. That way everybody wins: You learn new things in TikZ, this site has a new answer to a specific problem, and some person looking for something similar in the future will be able to find this question and (possibly, hopefully) many nice solutions.

But like this it's unlikely that anyone will profit much from this question: You got your answer, but I doubt that you learned a lot or will be enabled to draw the next complicated picture by yourself. So please first try for yourself. If then you have problems, post a specific question, include a minimal working example and possibly a picture.

Answer 2

you can try this

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows}
\begin{document}
            \def\ANGLE{25}    
\begin{tikzpicture}
\begin{scope}
\draw[fill=blue!50] (0,0) coordinate(O) -- (\ANGLE:5) coordinate(A) coordinate[pos=0.6](M) |- (O);
\draw (A)--++(\ANGLE:0.5)coordinate(P) ;
\draw (A) -- (P) circle (0.3);
              \begin{scope}[shift={(M)},rotate=\ANGLE]
                   \draw[fill=yellow]  (M) rectangle ++(0.6,0.6)coordinate(N);
                   \path (M) -- (N)coordinate[pos=0.5](G);
                   \path (N) |- (M) coordinate[pos=0.25](J);
                   \draw[red] (J) -- (J-|P);
                \end{scope}

                \begin{scope}
                \path(P) --++(0.3,0)coordinate(D);
                \draw (D) --++(0,-1)coordinate(K) --++(-0.3,0)coordinate(L) ;
                \draw[fill=green]  (L) rectangle ++(0.6,-0.6);
                \end{scope}             
\end{scope}
\end{tikzpicture}
\hfill
\begin{tikzpicture}
              \begin{scope}[shift={(M)},rotate=\ANGLE]
              \draw[dashed,gray,-latex] (G) -- ++(3,0)node[above]{$\overrightarrow{x}$};
              \draw[dashed,gray,-latex] (G) -- ++(0,3)node[right]{$\overrightarrow{y}$};              
                   \draw[fill=yellow]  (M) rectangle ++(0.6,0.6)coordinate(N);
                   \path (M) -- (N)coordinate[pos=0.5](G);
                    \path (N) |- (M) coordinate[pos=0.25](J);
                   \draw[red] (J) -- (J-|P);
                   \draw[red,-latex,thick] (G) -- ++(0,2)node[right]{N};
                   \draw[red,-latex,thick] (G) -- ++(-1,0)node[above]{T};
                   \draw[-latex] (J) -- ++(2,0);
                \end{scope}
                \draw[blue,thick,-latex] (G)node[right]{G} --++(0,-2)node[right]{P};
\end{tikzpicture}
\hfill
\begin{tikzpicture}
                \begin{scope}

                \draw[fill=green]  (L) rectangle ++(0.6,-0.6)coordinate(Q);
                \path(L) -- (Q) coordinate[pos=0.5](G2);
                \draw[-latex] (G2) -- ++(0,-1.5)node[right]{$m\cdot g$};
                 \draw[-latex] (G2|-L) -- ++(0,1.5)node[right]{$T'$};
                \end{scope}
\end{tikzpicture}
\end{document}

Answer 3

OK, I can understand. But I have no idea of how your figure will look like. From your question which talks of two vectors, may be this will help you to get started.

\begin{tikzpicture}
\draw[-stealth] (-1,0)  arc (-80.0026:40:1) ;
\draw [-latex,very thick] (-1,1)  -- node [above,near end,rotate=90] {$F_{g}$}(-1,-2);
\draw [-latex,very thick](-1,1) -- node [above,near end,rotate=48] {$F_{D}$} (1,3);
\node at (0,0.5) {$\alpha$};
\end{tikzpicture} 

PS: If you find it too difficult to hard code every thing, You look into inkscape Link. It is quiet easy to draw in inkscape. and then you can export your diagram using inkscape2tikz Link to tikz code.

EDIT You can useTikZEdt also. It is a semigraphical tikz editor having many tools for easy drawing.

If you want to experiment, I suggest you try kTikz / Qtikz also. Hope the beginning will not be bitter.