Acharged particle (q = −8.0 mc), which moves in a region where the only force acting on the particle is an electric force, is released from rest at point a. at point b the kinetic energy of the particle is equal to 4.8 j. what is the electric potential difference vb − va?

Explanation:

As we know that charge is released from rest and then at point B it is moving with kinetic energy K = 4.8 J

so here by mechanical energy conservation law we can say that gain in kinetic energy of the charge is equal to the loss in electrostatic potential energy.

so here we can say

layer a is the exosphere and layer b is the thermosphere.   is the answer i think but i hope this .