If instead of writing down the Euler-Lagrange equations straight away for some system, say a block on a freely moving inclined plane, I were to first write down the action that was to be minimized,(adsbygoogle = window.adsbygoogle || []).push({});

[tex]S = \int_{t_{1}}^{t_{2}}L(q,q',t)dt[/tex]

what would I take to be t_{1}and t_{2}supposing that I needed to solve for the accelerations of the block and plane?

Also, I would require that my q(t_{1}) and q(t_{2}) were given so that when I integrate by parts, I get the usual eqns of motion. What would I take for these values? Let us say, that in this specific problem, the block starts off at the top of the plane at t = 0.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Start from the Action

**Physics Forums | Science Articles, Homework Help, Discussion**