Finding force on a charge from an electric potential field

[martinpeim16]

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

E=-(grad)V

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 I am stuck here.

Thanks in advance

 

[Redbelly98]

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.

That equation is true no matter what E is due to.
Is this a homework problem?