FYKOS Year 25 Series 5 Problem 2 — electric equilibrium · FYKOS 25 #25.5.2

Physics · mechanics · electromagnetism

Problem

An insulating rod of length

d

and negligible mass can rotate around its middle point (see picture). There are small balls of negligible mass and charges

Q_{1}

and 2

Q_{1}

on both of its ends. Due to the weight

G

(see picture) the system is in mechanical equilibrium. Distance

h

under each of the small balls is a another ball with charge

Q

. What is the distance

x

for which the rod is horizontal and is in equilibrium? What is the distance

h

such that the rod is in equilibrium but there is no force on the pivot that holds it?