A conservative force $\overrightarrow{F}$ is in the $+x$-direction and has magnitude $F(x) = a/(x + x_0)^2$, where $\alpha = 0.800$ N $\cdot$ m$^2$ and $x_0 = 0.200$ m. (a) What is the potential-energy function $U(x)$ for this force? Let $U(x) \rightarrow 0$ as $x \rightarrow \infty$. (b) An object with mass $m = 0.500$ kg is released from rest at $x = 0$ and moves in the $+x$-direction. If $\overrightarrow{F}$
is the only force acting on the object, what is the object's speed when it reaches $x = 0.400$ m?