Electric Potential of 2 Point Charges

AI Thread Summary
The discussion focuses on calculating the speeds of two charged spheres, C and D, at the moment of collision. Sphere C has a charge of 2nC and a mass of 1g, while sphere D has a charge of -1nC and a mass of 2g, starting 10mm apart. The energy conservation principle is applied, stating that the initial total energy equals the final total energy, as both spheres start from rest. One participant suggests reframing the energy equations to reflect the total energy of both spheres rather than comparing them individually. The conversation emphasizes the importance of correctly applying energy conservation in the context of the problem.
vforvirginia
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Homework Statement


The 2.1mm diameter spheres in the figure are released from rest. What are their speeds vc and vd at the instant they collide?

Spheres:
C has 2nC of charge and a mass of 1g.
D has -1nC of charge and a mass of 2g.
The starting distance between the two spheres is 10mm. Each sphere as a diameter of 2.1mm.

Homework Equations


V=(1/4pi*ε_0)*Q/r
Q is the charge and r is the distance between the two spheres.
K=.5*mv^2


The Attempt at a Solution


ΔKC+ΔUC = 0 = ΔKD+ΔUD
Ki for spheres C and D are 0 since the spheres begin at rest:
KCf+UCf-UCi=KDf+UDf-UDi

The rest of my attempt is basically putting the numbers in and solving for KCf in terms of KDf and then using that to get KDf. I just want to know if I am heading in the right direction.
 
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Hi vforvirginia! welcome to pf! :smile:

In your energy conservation equations you are comparing the energies of two different balls and making them equal. I think that should be re-framed as, the total energy of the balls initially is equal to their total energy at the end.
 

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