The Electric Potential Difference Created by Point Charges

In summary: The initial momentum is zero so the final momentum is also zero. Use the momentum formula and the fact that the two particles have the same charge to find the initial separation.In summary, the problem involves two particles with different masses and the same charge being released and flying apart due to the conservation of energy. To find the initial separation between the particles, the potential difference between the two states is calculated and equated to the kinetic energy of the particles. The conservation of momentum is also used to find the initial separation, as there is no external force acting on the particles.
  • #1
eclecticist
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Homework Statement


One particle has a mass of 3.00 10-3 kg and a charge of +7.50 µC. A second particle has a mass of 6.00 10-3 kg and the same charge. The two particles are initially held in place and then released. The particles fly apart, and when the separation between them is 0.100 m, the speed of the 3.00 10-3 kg particle is 130 m/s. Find the initial separation between the particles.

Homework Equations


V = kQ/d
Vq=W
W=KE=1/2mv^2


The Attempt at a Solution



I don't really know where to start. I haven't seen any problems asking for initial separation before so I would appreciate it if someone could point me in the right direction.
 
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  • #2
The basic principle is the conservation of energy. Start by finding the potential difference between the two states, one at separation d(say) and the other at separation 0.1m. This difference manifests as the kinetic energy of the particles. Can you proceed?
 
  • #3
I understand that, but in order to calculate the kinetic energy of the particles, I need to know the speed of the other particle as well, because energy is conserved, which isn't given, so I'm not sure what to do after that. Also, if I'm not mistaken, mass doesn't affect the potential difference of a charge, right?
 
  • #4
What about conservation of momentum, there is no external force so linear momentum is conserved.
 

1. What is electric potential difference?

Electric potential difference, also known as voltage, is a measure of the difference in electric potential energy between two points in an electric field. It is the amount of work required to move a unit charge from one point to another, and is measured in volts (V).

2. How is electric potential difference created by point charges?

Electric potential difference is created by point charges through the Coulomb's Law, which states that the force between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them. As the distance between the point charges decreases, the electric potential difference increases.

3. What is the formula for calculating electric potential difference?

The formula for calculating electric potential difference is V = kQ/r, where V is the potential difference, k is the Coulomb's constant (9 × 10^9 N·m^2/C^2), Q is the magnitude of the point charge, and r is the distance between the point charge and the point at which the potential difference is being measured.

4. How does the direction of electric potential difference relate to the direction of the electric field?

The direction of electric potential difference is opposite to the direction of the electric field. This means that if the electric field is pointing from the positive to negative charge, the electric potential difference will be in the opposite direction, from the negative to positive charge.

5. Can electric potential difference be negative?

Yes, electric potential difference can be negative. This occurs when the direction of the electric field and the direction of the movement of a positive charge are opposite. In this case, the electric potential difference is negative because the electric field is doing work against the movement of the charge.

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