Two point charges lies on the x-axis. A charge of +9.9uC is at the origin and a charge of -5.1uC is at x=10cm. At what position would a third charge q3 be in equilibrium? How are we suppose to do that if we don't know what the charge of q3 is??

Question

anonymous · Answer

And can someone define equilibrium? Is that no net force?

kainui · Answer

Yep, equilibrium is when the forces in one direction are cancelled by the forces in the opposite direction.

kainui · Answer

Since you don't know what the charge of q3 is exactly, don't let that confuse you. Just go about doing this problem with q3 as a variable. I think you'll find that the location of Q3 isn't dependent upon its charge once you solve it. =)

anonymous · Answer

Im an idiot I figured it out set the two forces equal divide by q3

anonymous · Answer

Been out of the physics game for a couple of months thanks for your kind response most people would have trolled.

kainui · Answer

Lol it's weird in a lot of physics problems you end up playing around with numbers and variables and sometimes the variables divide out. I generally like to solve all my physics problems using only variables and at the very end plug in all my amounts to avoid confusion.

For example, I know the units of velocity, but if I plug in 25 m/s I might end up just plugging in 25 and forget what that means and mess up.

anonymous · Answer

is the distance of charge from -5.1 uc charge is 25.47cm.