What happens to the force between two charges if the magnitude of both charges is doubled and the distance between them is cut in half?

think its the third option

the bal will not change its velocity.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west