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# A Nonlinear Approximate Solution to the Damped Pendulum Derived Using the Method of Successive Approximations

## Abstract

An approximate analytic solution to the damped pendulum is derived using the method of successive approximations to obtain a nonlinear approximation for the system. We take the approximate solution to the undamped pendulum using the method of successive approximations and compare it to the damped pendulum solution when a linear approximation is used. By looking at these two solutions, we can make an educated guess about the form of the general, approximate solution to the nonlinear damped pendulum. By adjusting the initial guesses and the initial conditions, we derive approximate solutions in three ways. Using MATLAB, the approximate solutions are compared to the full numerical solution through the Euler-Cromer method. To determine how accurate the approximations are, the errors of the approximations are calculated relative to the full numerical Euler-Cromer solution. Each new approximation came with a significant decrease in error, with the final error being 0.0099. This resulted in an improvement to the method of successive approximations. Finally, our best approximation is compared to an available and previously published work.

## Acknowledgements

This work was supported by a grant from SEEP (STEM Education Improvement Plan)

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