Charged Particles on a pendulum

31
0
1. The problem statement, all variables and given/known data

What is the distance(d) separating the charged particles dangling on the pendulum?

Length of Nonconducting string=120cm
mass of particles= 10g
Charge q = 1.2*10^-8


2. Relevant equations

Fe=(k*q^2)/d^2



3. The attempt at a solution

I think I could get this problem easily if I had either the angle between verticle and the nonconducting string or the electric force opposing the masses. I have been using my knowledge of trigonometry to figure this out and trying to manipulate the above equation, but with no luck. Just needed to be pointed in the right direction I think. Thanks!
 

Dick

Science Advisor
Homework Helper
26,249
611
Focus on one of the particles. You have three forces on the particle, gravity, electrical, and the tension force of the the string. They all have to balance (i.e. the sum is zero). Split each one of them into xy components and express them in terms of the unknown angle theta. Start writing down the equations you get, ok?
 
31
0
ok.... I will show you what I have. I don't know Fe or Theta.....That is where I am hitting a roadblock. mg= .098N

Fe=Tsin(theta)
mg=Tcos(theta)
Fe/mg=Tan(theta)

Am I still overlooking something?
 

Dick

Science Advisor
Homework Helper
26,249
611
You can also express Fe in terms of sin(theta), since the distance is a function of sin(theta).
 
Last edited:

The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top