In the diagram below, there are three collinear point charges: q_1, q_2, and q_3
ID: 1652120 • Letter: I
Question
In the diagram below, there are three collinear point charges: q_1, q_2, and q_3. The distance between q_1 and q_2 is the same as that between q_2 and q_3. Rank the six combinations of electric charges on the basis of the electric force acting on q_1. Define forces pointing to the right as positive and forces pointing to the left as negative. Rank positive forces as larger than negative forces. Rank from largest to smallest, placing the largest on the left and the smallest on the right. To rank items as equivalent, overlap them.Explanation / Answer
F = kq1q2/r2 + kq1q3/(2r)2 = (kq1/r2)(q2 + q3/4)
taking k/r2 = K = constant
F = Kq1(q2 + q3/4)
also here positive forces will come in left, but as said in question, take right as positive
F = -Kq1(q2 + q3/4)
1) F1 = -K(-1)(-1 - 1/4) = -1.25K
2) F2 = -K(-1)(1 + 1/4) = 1.25K
3) F3 = -K(1)(-1 - 1/4) = 1.25K
4) F4 = -K(1)(-1 + 1/4) = 0.75K
5) F5 = -K(1)(1 - 1/4) = -0.75K
6) F6 = -K(1)(1 + 1/4) = -1.25K
F2 = F3 > F4 > F5 > F1 = F6