We can also write the differential equation in the more familiar form using primes. We can use the solutions to plot the position, velocity, and acceleration vs. time. Plot is a function which plots the given equation over a specified range. Mathematica can assign complicated functions to one variable to simplify what one needs to write. We can use Mathematica to quickly create lists of numbers, and to plot them.
Table evaluates a function at given intervals, and stores the numbers in a list.
Sometimes Mathematica's output contains extra parentheses. Flatten will remove them. ListPlot is a function which takes a list of numbers and plots a point for each one. We can find the period by looking at the 1st two minimums of the above plot. FindMinimum finds the minimum of a function around a given point.