Each sketch below shows three objects with an electric charge. In each case, dec

Question

Each sketch below shows three objects with an electric charge. In each case, decide whether ther is a net force, decide whether it pushes the green-ring object to the left or right. Then select the appropriate button under the sketch. for example, if there is a net force pushing the green-ring object in the first sketch to the left, select the left button under the first sketch. If there is no net force on the green-ring object in the second sketch, select the middle button under the second sketch. And so on. e is a net force acting on the object outlined in green. If there

Explanation / Answer

Electrostatic force is given by:

F = k*Q1*Q2/R^2

Force is attractive if both charges have different signs and Force is repulsive if both forces have same sign.

Part A.

Charge on green object due to +3 will be repulsive, towards left, and Charge on green object due to -3 will be attractive, towards right

Fnet = F13 - F12 = kq1*q3/r13^2 - k*q1*q2/r12^2

if we assume distance for 1 box is 1 m, then

q1 = +3, q2 = +3, & q3 = -3

q1 = q2 = q3

r12 = 3 m

r13 = 6 m

Fnet = k*q*q*(1/6^2 - 1/3^2) = -0.0833*k*q^2

So force is negative which means towards left.

B.

Charge on green object due to (-2 on left) will be repulsive, So force will be towards left,

And Charge on green object due to (-2 on right) will be repulsive, So force will be towards right,

Fnet = F12 - F13

Fnet = k*q1*q2/r12^2 - k*q1*q3/r13^2

Now as we can see

q1 = -3

q2 = -2, & q3 = -2

q2 = q3

r13 = r12

Fnet = k*q1*q2/r12^2 - k*q1*q3/r13^2 = k*q1*(q2/r12^2 - q3/r13^2)

from above observations q2 = q3 & r12 = r13,

(q2/r12^2 - q3/r13^2) = 0

Fnet = 0 N

C.

Charge on green object due to (+3 on left) will be attractive, So force will be towards left,

And Charge on green object due to (+1 on right) will be attractive, So force will be towards right,

Fnet = F13 - F12

Fnet = k*q1*q3/r13^2 - k*q1*q2/r12^2

Now as we can see

q1 = -3

q2 = +3, & q3 = +1

r13 = r12

Fnet = k*q1*q3/r13^2 - k*q1*q2/r12^2 = k*q1/r13^2*(q3 - q2)

q3 - q2 = 1 - 3 = -2

Fnet = -2*k*q1/r13^2

Since force is negative, So direction will be towards left.

Please Upvote. Comment below if you have any doubt.

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