The equation of motion of a particle is $x = A \, \mathrm{cos}\left[(\alpha t)^2\right]$. What type of motion is it?
The answer to this question in my textbook was: "Oscillatory but not periodic". How is this possible? The first line of my textbook says: "Every oscillatory motion is periodic but not every periodic motion is oscillatory." So, is the answer provided incorrect, or is my textbook incorrect?
I think this has something to do with time being a quadratic function, but I can't seem to think any further. This isn't one of those usual SHM equations you see.
Question: Is the motion $x = A \, \mathrm{cos}\left[(\alpha t)^2\right]$ oscillatory, periodic, both or neither?