point charge attractioning a positive charge from infinity to 30cm

goWlfpack

1. The problem statement, all variables and given/known data

A point charge of 2.0 10-9 C is located at the origin. How much work is required to bring a positive charge of 4.0 10-9 C from infinity to the location x = 30.0 cm?

and it requests the answer in J

2. Relevant equations

W=-q2(delta)V

DeltaV = Ke q1/d

where delta v is potential difference, W is work, q2 and q1 are the charges, Ke is coulombs constant, and d is distance



3. The attempt at a solution

I plugged in all of the variables using 4.0 *10 ^ -9 as my q1 and 2.0*10^-9 as my q2 and that was wrong so i switched them.. again wrong..

Doc Al

Switching q1 and q2 won't change anything. Show your final expression for the work done and the numbers you plugged in. Is it positive or negative?