CK-12 Foundation
Ck 12 Exploration Series: Simulations: Physics: Portrait Gallery
[Free Registration/Login Required] Learn about adding force vectors in two dimensions using the example of a painting hanging from two strings. Experiment with variables of weight and angles to hang a portrait in this physics simulation....
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Libros Vivos: Fuerzas en Equilibrio
This site has a simple introduction to equilibrium of force and moment of a force.