Need to find force on a charge due to an electric field strenght, pls help

1. Apr 15, 2010

martinpeim16

i have a problem asking about a Electric potential field(V), form which i have to find the electric field strength vector(E).

After i did this, it asks me to find the force on a charge at a point P.

i know F=qE but this is when i have a E field due to a another charge on space, but here i have a vector field.

I need help on knowing what i can do next coz im stuck here.