Answer
(a) $U_{1 \to 2}=U_{1 \to 3}$
(b) $v_{2}=v_{3}$
Work Step by Step
(a) Potential energy of the charge in an electric field is $U=qEs$.
Here, $s$ is the distance measured vertically from point $1$ to point $2$ as there is no horizontal component of $E$.
Hence, $U_{1 \to 2}=U_{1 \to 3}$
(b) Since, total energy is constant , the change in the kinetic energy $\Delta K_{12}$ is equal to $\Delta K_{13}$ because $\Delta U_{12}=\Delta U_{13}$.
Hence, $v_{2}=v_{3}$.
