Three point charges are arranged in a horizontal line as shown below. Find the e

Question

Three point charges are arranged in a horizontal line as shown below. Find the electric forces (in units of kQ2/R2) on the charges given the following: Q12 Q, Q216 Q, Q3 = 18 Q, r1 1 R, and r2-2 R. Remember that a positive force points to the right and a negative force points to the left Q5 What is the net force on charge Q1? -28.0 kQ2/R2 Incorrect. Computer's answer now shown above Tries 2/2 Previous Tries What is the net force on charge Q2? 104 kQ2/R2 The total force on Q2 is going to be a vector sum of F21 (the force on Q2 due to Q1) and F23 (the force on Q2 due to Q3) You need to find both the and F23 The magnitudes of the forces are given by F21 = kQ2Q1/r12 and magnitudes and directions of F21 F23 kQ2Q3/r22, where k = 9e9 Vm/C and the absolute values for all charges should be used The direction of each force is determined by the two charges, where opposite charges attract and same charges repel Submit AnswerIncorrect. Tries 1/2 Previous Tries What is the net force on charge Q3? kQ2/R2

Explanation / Answer

a. net force on Q1= force due to Q2 on Q1 + force due to Q3 on Q1

= kQ1Q2/r12 + kQ1Q3/(r1+r2)2

= k(-2Q)(-16Q)/R2 ( towards left) + k(-2Q)(18Q)/(3R)2 (towards right)

=32kQ2/R2 ( towards left) + 4 kQ2/R2 (towards right)

= 28kQ2/R2 ( towards left)

as force pointing towards left is -ve

=-28 kQ2/R2

b. net force on Q2= force due to Q1 on Q2 + force due to Q3 on Q2

= kQ2Q1/r12 + kQ2Q3/(r2)2

= k(-2Q)(-16Q)/R2 ( towards right) + k(-16Q)(18Q)/(2R)2 (towards right)

=32kQ2/R2 ( towards right) + 72 kQ2/R2 (towards right)

= 104kQ2/R2 ( towards right)

as force pointing towards right is +ve.

= + 104 kQ2/R2

c. net force on Q3= force due to Q2 on Q3 + force due to Q1 on Q3

= kQ3Q2/r22 + kQ1Q3/(r1+r2)2

= k(18Q)(-16Q)/(2R)2 ( towards left) + k(-2Q)(18Q)/(3R)2 (towards right)

=72kQ2/R2 ( towards left) + 4 kQ2/R2 (towards left)

= 76kQ2/R2 ( towards left)

as force pointing towards left is -ve

=-76 kQ2/R2

d. sum of the forces on all three charges = Force on charge Q1 + Force on charge Q2 + force on charge Q3

= -28 kQ2/R2 + 104kQ2/R2 -76kQ2/R2=0

all the best in the course work

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