Help!!! A Three Charge System???

Question

Two point charges are located on the x axis: one charge, q1= -16.0nC , is located at -1.685m ; the second charge, q2= 38.5nC , is at the origin .

What is the net force exerted by these two charges on a third charge q3 = 53.5nC placed between q1 and q2 at x3 at = -1.065m ?

Note that your answer may be positive or negative, depending on the direction of the force.

Use 8.85×10−12nC^2 / (N*m^2) for the permittivity of free space.

Express the final answer in N units.

Thanks soooo much for your help!!! It's GREATLY appreciated!!!

Answer 1

Use F = q1*q2/(4πεr²)

Normally use vectors for this. Since these are all in a line, easier to do.

Using the equation on A (first point) and C, F=-2.00E-5 N. This is attractive, so pulls C in negative x direction.

Using the equation on B (2nd point) and C, F=1.63E-5 N. This is repulsive, so pushes C in negative x direction.

Careful of the signs. Positive means repulsion, negative means attract. Adding the two, F=3.635247E-5 N in negative x direction.