Finding the charge on two beads?

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The discussion revolves around calculating the charge on two positively charged beads positioned on an insulating string at a 60-degree angle. The beads, each with a mass of 0.1g, experience forces including gravity, electrostatic repulsion, and a normal force from the string. For the beads to remain at rest, the net force must equal zero, indicating a balance of these forces. Participants emphasize understanding the conditions necessary for equilibrium and the role of the normal force. The conversation highlights the importance of identifying all forces acting on the beads to solve the problem effectively.
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Homework Statement


Two small insulating spherical bead are placed on a taut(insulating, isolated) string which has a knot at its lower end. The string is stretched at an angle of 60degress to the horizontal. The beads can move frictionlessly on the string. The beads are given identical positive charges (which are distributed evenly over the tiny volumes of the beads). The lower bead rests against the knot. The other bead comes to rest 5cm away from the knot on the string. The mass of each bead is 0.1g. What is the charge on the beads?

Homework Equations




The Attempt at a Solution


Would I use work? Or something else? Not quite sure
Just an idea of even what equation to start with would be nice
 
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Think about how it is possible that the bead can remain at rest. What forces act on the bead?
 
well there would be the force that pushes the two beads apart, and gravity?
 
TSny said:
Think about how it is possible that the bead can remain at rest. What forces act on the bead?

Well there would be the force that pushed the two beads away, and gravity?
 
janetxo said:
Well there would be the force that pushed the two beads away, and gravity?

Yes. But there is a third force. Hint: The bead is in contact with the string.

What is the condition that must be met by these 3 forces for the bead to remain at rest?
 
TSny said:
Yes. But there is a third force. Hint: The bead is in contact with the string.

What is the condition that must be met by these 3 forces for the bead to remain at rest?

So, a normal force between the bed and the string? (as there is no friction). and the net forces would have to be 0 in order for it to be at rest. Fnet=ma=0.
 
janetxo said:
So, a normal force between the bed and the string? (as there is no friction). and the net forces would have to be 0 in order for it to be at rest. Fnet=ma=0.
Yes, that's right.
 
TSny said:
Yes, that's right.

thanks for walking me through that bit! Wasnt quite sure how to start, :) really apperiate it
 
Good work. Welcome to PF!
 

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