An Electric Force Problem (See Chapter
15, WebAssignment 6)
Two small conducting spheres are connected to
opposite ends of an insulating rod. The spheres carry charges as
indicated
in the drawing below. Two charged spheres are located on a second
insulating
rod as shown. Forces directed to the right are positive.
Strategy. There is an
electric force on each charge on the left hand rod due to each charge
on the right hand rod, so there are four electric forces on that rod
due to the other rod. The values and locations of all the charges are
known, so Coulomb's law can be used to calculate each force [(a)
through e)]. The sum of these forces is the net force on the rod [(e)].
The negative of this force is the net force on the right hand rod
[Newton's 3rd law, (f)].
(a) Use Coulomb’s law to calculate the force on q2 due to q3.
(b) Calculate the force on q2
due to q4.
(c) Calculate the force on q1
due to q3.
(d) Calculate the force on q1
due to q4.
(e) Calculate the sum of these forces (the net electrical force on
the
left hand rod due to q3
and q4).
(f) What is the net electrical force on the right hand rod due to q1
and q2?
Solution
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