# Creating a Free Body Diagram in TikZ

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.

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Please provide a picture of what you want (may be hand drawn or use some drawing software). – Harish Kumar Mar 25 '12 at 7:34
You can start with the sources for those images which are located on TeXample.net. – zeroth Mar 25 '12 at 7:38
Welcome to TeX.SE. It is useful to post what you have tried so far and then as a specific question about what you are unable to do. If you are just asking for general information on what drawing packages to use there are several good references on this site, but I'd personally recommend TikZ. – Peter Grill Mar 25 '12 at 18:14
If the answers below seem overwhelming, as they did to me when I started with TikZ, perhaps these two tutorial like answers might help you get started: How to draw a poset Hasse Diagram using TikZ? and How to draw a cube with TikZ where all faces have a distinct color? – Peter Grill Mar 25 '12 at 18:16

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 , so you could use a searching website of your choice and search for, say tikz manual. This would probably yields something like this:

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.

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I rarely down vote, but I did on this one, as the full example is shown in TeXample.net from where the images were copied. – Yiannis Lazarides Mar 25 '12 at 21:29
I appreciate you took the time to explain to the OP the cause of the down-votes and the steps he/she should follow to learn to use TikZ. – Gonzalo Medina Mar 25 '12 at 22:42

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}


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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.

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