Let \( f, g : \mathbb{R} \to \mathbb{R} \) be two functions defined by
\[
f(x) = \begin{cases}
x |x| \sin \frac{1}{x} & \text{if } x \neq 0 \\
0 & \text{if } x = 0
\end{cases}
\]
and
\[
g(x) = \begin{cases}
x^2 \sin \frac{1}{x} + x \cos \frac{1}{x} & \text{if } x \neq 0 \\
0 & \text{if } x = 0
\end{cases}
\]
Then, which one of the following is TRUE?