Excess electrons question


by ehdubbya
Tags: electrons, excess
ehdubbya
ehdubbya is offline
#1
Feb2-08, 01:55 PM
P: 1
1. The problem statement, all variables and given/known data
My problem states that a pith ball hangs at 20 degrees from the verticle and weighs 3 grams. It is moved 10cm by a charged rod. They both have the same charge. It asks what is the charge on the ball in C and approximatley how many excess electrons are on the ball.


2. Relevant equations
I have the equation kqq/rsquared


3. The attempt at a solution
I found all the sides to the triangle and I do not know where to go from there. I do not know the charges so how can I use the equation with q in it?
Phys.Org News Partner Science news on Phys.org
Cougars' diverse diet helped them survive the Pleistocene mass extinction
Cyber risks can cause disruption on scale of 2008 crisis, study says
Mantis shrimp stronger than airplanes
Tom Mattson
Tom Mattson is offline
#2
Feb2-08, 02:26 PM
Emeritus
Sci Advisor
PF Gold
Tom Mattson's Avatar
P: 5,540
Quote Quote by ehdubbya View Post
It is moved 10cm by a charged rod.
10 cm in which direction? x? y? other? And where is the rod in relation to the ball? Is the charge distributed over the entire rod, or is it concentrated at a point?



I found all the sides to the triangle and I do not know where to go from there. I do not know the charges so how can I use the equation with q in it?
Did you draw a free-body diagram and set up the equations from Newton's second law? You should have 2 equations in 2 unknowns (q and the tension T in the cord from which the ball hangs).


Register to reply

Related Discussions
Enantiomeric excess question Chemistry 3
how to find the number of excess electrons? Introductory Physics Homework 5
excess electrons or protons on drop. Introductory Physics Homework 3
excess electrons on a lead sphere Introductory Physics Homework 2
Excess electrons and net charge Introductory Physics Homework 3