Here's the answers F, is the force that g, alone feels is simply the vector sumb + h by considering them individually and then just adding superposition. (This important property will also be used when potential, magnetic fields, and magnetic forces.) The Principle of Superposition The net electric force on a charge (q) due to a collection of other charges (Q is equal to the sum of the individual forces that each of the Q's alone exerts on q. 20 rim 9 1X10-9 C 92 R Example 9-7: In the figure above, assume that 9, = 2 C, q, = -8 C, and 9; = R= 2 m, which one of the following vectors best illustrates the direction of the net A. C.YSICS AND MATH REVIEW 91 + 93 on 3 1-on- 3 + 2-on- 3 9193 = 9x 109 N . m (2 C)(1 x 10- C) C2 =18N (1 m)2 (repulsive; away from q,) 192 93 = 9 x 109 N . m (8 C)(1 x 10- C) R2 C2 = 18N (2 m) (attractive; toward q,) tion had asked for the magnitude of the net electric force on 93, then we'd use the Pytha o find the length of the vector Fog. The vector Fong is the hypotenuse of the right are Fjong and Fong , so the magnitude of Fong is found like this: 18 N (Fong ) = (F ) + ( F2-on-3 ) + L 102 18 N