Question

A point charge with a charge q1 = 2.90 μC is held stationary at the origin. A second point charge with a charge q2 = -4.10 μC moves from the point x= 0.170 m , y=0 to the point x= 0.250 m , y= 0.260 m .

Answer 1

Given poitn charges are q1 = 2.9 μC, q2 = -4.10 μC

charge q2 is moving form say r1 to r2

   r1 is (0.170m,0m)
   r2 is (0.250m,0.170m)

now the distance from origine to the point r1 is = sqrt((0-0)^2+(0.170-0)^2) = 0.17 m
                   r2 is = sqrt((0.25-0)^2+(0.260-0)^2) = 0.361 m

nwo the work done by the electric force on charge q2 is = change in potential energy

  
   W = kq1q2(1/r2-1/r1)
   = 9*10^9*(2.9*10^-6)(-4.10*10^-6)( 1/0.361-1/0.17) J

   = 0.3330J
Work done W = 0.3330 J