## Another worked Landau pendulum problem

Posted by peeterjoot on July 14, 2012

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## Question: Pendulum with support moving in line

This problem like the last, but with the point of suspension moving in a horizontal line .

## Answer

Our mass point has coordinates

so that the velocity is

Our squared velocity is

In the last term, we can reduce the sum of sines, finding a total derivative term and a remainder as in the previous problem. That is

Putting all the pieces together and dropping the total derivatives we have the stated solution

# References

[1] LD Landau and EM Lifshitz. *Mechanics, vol. 1*. 1976.

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