The electrostatic potential difference VB - VA between two points A & B, corresponding to electrostatic forces, is defined as the change

The electrostatic potential difference VB - VA between two points A & B corresponding to electrostatic forces is defined as the change in electrostatic potential energy per unit charge as it moves from A to B. A charged particle of mass 0.02 kg moves under electrostatic forces only from A to B having potential difference of 10 volts as shown. Velocity of the particle at A is 20 m/s and at B is 40 m/s and their directions are perpendicular. Calculate the charge q on the particle.

Since potenitial is a scalar quantity.